Koseki Bijou

This name is officially written using the Japanese name format; the family name is Koseki.

Koseki Bijou (古石ビジュ―), commonly known as Biboo, is a female English speaking Virtual YouTuber associated with hololive. She debuted in 2023 as part of hololive -Advent-, the third generation of members of hololive English, alongside Shiori Novella, Nerissa Ravencroft, Fuwawa Abyssgard and Mococo Abyssgard.

Kira kira, koseki!

Basic Details: Original Name: 古石ビジュ―

Nickname(s): The Jewel of Emotions Biboo Oobib (Evil Alter) Chadseki Bidet Bagel Bimbo Bejo (by Kobo Kanaeru) Beebs Beejoe (by Kaela Kovalskia) Batu Joe Agent 4'7" The Stone that is Approaching The Stain Princess (ENreco) Lil'Rock

Debut Date: YouTube: 2023/07/30

Character Designer: Illustration: Kitada Mo (main) Ryota (Pajama)[1] Design: Ninomae Ina'nis (Monster Hunter Wilds Costume)[2] Live2D: Otsukue[3] 3D Model: Amagai Rei[4] 81800 Model: Yoolie (Model)[5] Hash (January 2026 Face Tracking)[6]

Affiliation: hololive English

Personal Details: Gender: Female

Age: Above 18+

Birthday: 14 April

Height: 140 cm (4'7")[7]

Zodiac Sign: Aries

Fan Name: Pebbles

Emoji: 🗿

Profile: "I hope you'll feel my radiance!"

Formed from the crystallization of all forms of human emotion, Koseki Bijou is "The Jewel of Emotions." Over years and years, emotions of beauty and filth alike have woven into her under immense pressure, resulting in an unmatched brilliance.

Her ancient, mystic brilliance caused strife between the masses of the greedy, who fought over ownership of her. This led to her being imprisoned in secrecy, far from the reach of humans.

It seems as though when she encounters people, and particularly their good emotions, her radiance shines even brighter.

Personality: Biboo is bubbly, friendly, and often easily excited. She has an extensive knowledge of Gen Alpha memes (often leaving her slightly-older genmates and other members of hololive somewhat baffled) and frequently amuses her fellow members and her viewers with her childlike antics. Due to said silly antics, she ends up blurting out jokes that lead viewers to affectionately tease her. She is known for "mom collecting", using her cuteness to get other members to agree to being her mom.

She is also known for her RPG and action gaming skills (often coming up with challenges to make difficult games she's already cleared even harder), and has demonstrated knowledge of game modding, such as when she replaced Sans from Undertale with Mori Calliope for her hololive audition.

Despite her proclivity toward memeing and action games, she is one of the most "seiso" members of hololive English; she consciously refuses to swear on stream, instead literally saying "beep" in place of a swear word, even when reading out text from media that otherwise contains profanity. She also consistently uses "dang it!" to express frustration instead of harsher language, and relatedly, she has become well-known for remaining calm and collected even in the face of game challenges that would leave most other members of any branch hopelessly infuriated and upset. One of her chat emotes is even an all-caps "BEEP" and, although it is not an official channel rule, she asks that Pebbles also refrain from profanity in chat during streams if possible.

Appearance: She has long, silvery-purple hair with darker purple eyes. On her head she wears a dark purple crown. She has metallic pink wings and also has purple gemstones embedded or protruding on various parts of her body, most notably a large chest jewel, and small gems under her right eye and on the back of her hands. Despite appearances, her feet are not made out of gemstone and instead she has regular human feet encased in gemstone that she can remove at will. Her default hairstyle consists of hair flaps, double parted center-flap bangs and sidelocks.

History: Background: Following the debut of hololive English second generation -Council-, hololive English announced a permanent English language audition page on 30 December 2021.[8] An update to the audition page on 7 September 2022 sparked speculation of an upcoming English third generation.[9]

Bijou first discovered hololive from YouTube clips after the -Myth- debuts in 2020. She was inspired to audition for hololive, despite having no experience streaming at that time. Despite initially being rejected, she decided to focus all her efforts on her goal of joining. She applied three times before she was successful.[10]

At the audition, Bijou demonstrated her technical, gameplay and creative talent by playing her own fan-made mod of Undertale, defeating the boss Sans, who she had replaced with Mori Calliope.[11] Later, she recalls that when she learned she had been selected to join hololive, she was listening to the song I Really Want to Stay at Your House from the game Cyberpunk 2077.[12]

Koseki Bijou's YouTube and Twitter accounts were originally created on 11 May 2023, although they contained no content at this point. In early production, her codename was "Fairy."[13]

The third generation of hololive English, -Advent-, was first teased on the hololive English Twitter account with a short video on 22 July 2023.[14] This was followed by another teaser video on 23 July, showing five new characters.[15]

On 25 July, the hololive English YouTube channel posted a video titled Wanted!, revealing the five members of -Advent- and announcing their upcoming debuts.[16] At the same time, Bijou also posted a short teaser video on her YouTube channel and made her first tweet.[7][17]

All -Advent- members' YouTube channels reached 100,000 subscribers within twelve hours of the announcement.[18]

Debut: Bijou made her debut stream on 30 July 2023, from 12:45 PM to 1:30 PM JST (Saturday, 29 July 2023 at 8:45 PM to 9:30 PM PDT). The stream reached over 128,000 viewers at peak, featuring a magical girl opening and a PowerPoint presentation. It was followed by the release of her first cover, "Kyoumen no Nami." She reached over 200,000 YouTube subscribers during her debut stream.[19]

In hololive tradition, this was followed by the generation all-member group collab stream. This was in turn followed by the release of their first group song, "Rebellion."

Bijou did not rehearse too much for her debut, believing that the un-scripted and natural approach was best. However, she did work hard to prepare things for the event, and had a general plan.[12]

2023: On 1 August, Bijou reached 300,000 subscribers on her YouTube channel.

On 6 August, she celebrated her YouTube channel monetization and also enabled Super Chat feature.[20]

On 23 August, she reached 400,000 subscribers on her YouTube channel.

On 27 August, she opened her YouTube channel's membership feature and celebrated it with a gameplay stream of Rock Simulator.[21]

On 8 December, hololive English's Twitter account announced that -Advent- would debut their second 2D costumes.[22]

On 13 December, Bijou reached 500,000 subscribers on her YouTube channel.[23] This makes her the 59th hololive member to reach this milestone, and the fourth of her generation.

2024: On 1 January, hololive's Twitter account announced -Advent- second costumes reveal streams would be rescheduled due to the earthquake in Japan.[24]

On 5 January, Bijou debuted her new year costume. She has big braided twintails decorated with big purple ribbons. Bijou wears a light blue kimono that turns purple near the bottom. Her obi is purple and white. The lower half of the kimono has a butterfly and rose pattern, and has a ruffled diagonal cut. Bijou uses black boots. She can also use a light purple hat decorated with roses and a pacifier.[25][26]

On 29 May, hololive's Twitter announced that -Advent- would get their 3D models during summer.[27] The announcement on 11 July stated that Bijou's 3D debut stream would take place on 3 August.[28]

On 2 June, she reached 600,000 subscribers on her YouTube channel during a stream of the game Elden Ring.[29][30]

On 3 August, Bijou debuted her 3D model. During the stream, she performed an original song "Prism no Mahou."[31]

On 31 August, as part of the ENigmatic Recollection project, hololive English members debuted a new accessory for their main 2D costumes. They wear the white and blue cloaks first seen in the project's introduction video and related concept art. The cloak includes a blue gem containing a symbol that represents their affiliated guilds.[32]

On 6 October, Bijou released her first solo original song "Prism Magic."

On 7 November, she reached 700,000 subscribers on her YouTube channel.[33]

On 20 December, Bijou and other members debuted their 3D Santa costumes. The costume has two versions, white and red.[34]

2025: On 16 January, Bijou debuted her third 2D costume, named 81800. Bijou has two hairstyles, bob haircut and high-long twintails, both have her bangs covering her left eye which can also be covered by a black eye patch. On her face, she can also use various band aids. Bijou wears a strap, black top with various belts and frills. She uses a black, miniskirt with a big zipper to the side with a black, diagonal belt that carries a katana. Bijou has asymmetrical socks in black and gray. Bijou uses sneakers covered in gems. Bijou can wear a black jacket with a GEOW shaped hoodie, the inner is litmus blue, on the front the jacket has some patches including a Moai and the 81800 code. She can also hold her katana but not unsheathe it.[35][36]

On 27 February, during an Advent's friendship test collab featuring their casual costumes, each member had a hairstyle swap. Bijou has Mococo's main hairstyle including the dog ears.[37]

On 28 February, Ina, Bijou, Gigi and Raora debuted new Palico mascots as part of a sponsor by Monster Hunter Wilds.[38]

On 8 March, she debuted her hololive 6th fes. Color Rise Harmony 3D idol costume during the event's day 1 STAGE 1. The costume has some variants, it can be black or white, complemented with a color representative of the talent. The midriff can be covered or not. One has variant has a skirt while the other uses pants, with one leg exposed. Aside for the design featured in promotional material, the costume also includes a short jacket.[39]

On 22 March, she reached 800,000 subscribers on her YouTube channel.[40]

On 1 April, Shiori, Nerissa and Bijou, debuted buff 3D models.[41]

From 17 June until the end of the month, Bijou took a two-week hiatus for a work-related trip and a holiday trip. Pebbles referred to it as an absence of almost 140 years. Raora took care of John Cat in her absence.[42]

On 29 July, Bijou debuted new expressions for her 3D model.[43]

On 4 August, -Advent- announced a project to celebrated their second anniversary, including "The Story of Advent", a five chapter series corresponding to five original songs about the journey of them, a holo no graffity episode, and a 3D live "On the Run!" on 29 August.[44][45] A prologue video and their third original song "Genesis" were released on the same day.

On 29 August, during their second anniversary live "On the Run!", -Advent- debuted their 3D swimsuits first introduced in the hololive Summer 2023 event. The 2023 swimsuits are inspired in a sailor uniform. Members wear a two layered swimsuit, the first layer is blue from the straps going down diagonally to the center where each member has a mostly blue bow but one of the sides and the brooch are in one color representative of each member. The rest of the top is white. The edge has a semi circular cut. The lower piece of the first layer has two variants, one is a two layered blue skirt decorated with a white belt, a golden chain with some decorations hanging from it and a bow to the left and planks to the right. The second version is mostly the same but they wear blue shorts instead of a mini skirt. The second layer of the outfit is a matching striped bikini in white and another color depending on the member.[46]

On 17 October, Bijou debuted her third 2D costume as a new 3D costume in VRChat.[47] She also announced that she would be doing a 3D live on 1 November.

On 1 November, Bijou debuted her second original song "ROCK IN!"[48]

On 4 November, she reached 900,000 subscribers on her YouTube channel.[49]

On 15 November, Bijou held her first Twitch stream, reaching 1,944 viewers at peak.

On 15 December, Bijou and Ina debuted new 2D costumes as a part of a collaboration with the game Monster Hunter Wilds. This is Bijou's fourth 2D costume. She has loose, messy hair with dark purple tips, decorated with dark ribbons, she can use a headband with purple horns. Bijou wears a crossed strap, black dress. She has long, black, leather boots, with gems in the tip that resemble claws.[50]

2026: On 5 January, Bijou released new expressions for her third 2D costume in VRChat.[51]

On 9 January, she debuted her fifth 2D costume. She has two hairstyles, long loose hairstyle and low twintails. She can also use the long loose hair style for her third 2D costume and use a Pebble's shaped sleep mask. Bijou wears white and lilac pajamas with frills. She has asymmetric striped socks and Pebble-themed slippers. Bijou can wear a white T-shirt with one of two designs: an outline of a sad Bijou with a speech bubble saying "Don't talk to me I'm sad." or a sleeping Pebble with "Good Night" written below. The designs can be animated.[52]

Events: On 5 January 2024, hololive Twitter account announced a collaboration with CAPSULE on a "Cheer UP" themed pop-up store, featuring Kaela Kovalskia, Kobo Kanaeru, Oozora Subaru, Usada Pekora, Gawr Gura, and Koseki Bijou in Cheer up themed costume goods, and other activities. The store would be open from 27 January to 4 February 2024 in Taipei, Taiwan.[53] On 6 June 2025, hololive announced "hololive night," a collaboration with Los Angeles Dodgers baseball team, featuring Koseki Bijou, Ninomae Ina'nis, and IRyS in commercials, merchandise, food, and drinks, as well as various activities, including a live stream from Dodger Stadium. The event took place on 5 July 2025, and anyone who purchased a ticket received three exclusive trading cards featuring the talents in the Dodgers uniform.[54][55]

Mascots and fans: Her fans are called Pebbles. Her YouTube channel members are called Gemlins. The tier 2 members are called The Boulders, and the tier 3 members are called Moai Moai Kyun. She encourages her fans to draw their Pebble Persona, and post them in the hashtag #pebblesona. On 3 August 2024, during her 3D debut, Bijou introduced a new mascot called "Grand Executioner of Worlds" or "GEOW" for short. GEOW looks like a small, lilac mammal with rabbit-like characteristics and a jewel in his forehead.[56] Bijou claims to have been friends with GEOW for a long time, even before she was in jail.

Quotes: "Dang it!" "KAELA!" (to the tune of Clean Bandit's Symphony) "I just wanna be part of your skibidi, yeah! Will you hold my gyatt & not let go? Skibidi... Like a rizz song on the radio!"[57] "Bweh."

Relationships: Bijou is part of following groups:

"-Advent-," alongside Shiori Novella, Nerissa Ravencroft, Fuwawa Abyssgard and Mococo Abyssgard. "Grindstone," alongside Kaela Kovalskia. "Diamond Dogs," alongside Fuwawa Abyssgard and Mococo Abyssgard. "JewelBird," alongside Nerissa Ravencroft. "GraveStone," alongside Kureiji Ollie. "TombStone," alongside Mori Calliope. "Stone Age," alongside Nanashi Mumei. "BaeBi," alongside Hakos Baelz. "TakoRocky" or "Wooden Shovel," alongside Ninomae Ina'nis. "Killing, Two Birds, with One Stone," alongside Mori Calliope, Takanashi Kiara, and Nerissa Ravencroft, formed during a Baldur's Gate 3 collab. "The Sweaty TryHard Gamers," alongside Ceres Fauna, Hakos Baelz, and Kaela Kovalskia, formed during a PlateUp! collab. "Cerulean Cup," alongside Ninomae Ina'nis, IRyS, Ouro Kronii, and Gigi Murin. They are guildmates within the ENigmatic Recollection story. "Graondstone," alongside Kaela Kovalskia and Raora Panthera. "Goth Rock," alongside Shiori Novella. "Red Stone," alongside Akai Haato.

Trivia: Name: Koseki is a Japanese surname. She writes it with the kanji 「古石」, which are normally used to write this surname. "Kouseki" also means "crystal" or "mineral." It is similar to the word houseki「宝石」(gemstone). Bijou is a word of French origin, referring to a type of jewelry. She writes it in katakana, normally used to write loanwords from other languages. It is pronounced "bi-joo." In Japanese, "bijo" 「美女」 means "beautiful woman," and is also a female given name, written with the same kanji. However, it is pronounced differently, 「びじょ」(bijo), i.e. with a short o rather than a long o. She writes her name in Japanese name order. She is the only member of her generation to do so, and the only one to use kanji in part of her name. She is commonly called by the nickname Biboo, which is used both by fans and other EN members. In fact, she is called Biboo more than she is called Bijou.[58] Even staff call her Biboo.[59] When speaking in Japanese, she uses "Biboo" or "Bijou" in the third person instead of personal pronouns like "watashi."[60]

Lore: The members of Advent were sealed away in The Cell, a prison deep underground built to hold dangerous people and things. Its location is a closely-guarded secret.[61] Bijou was originally captured by being lured in with cake.[62] During their escape, Shiori Novella was able to pick up Bijou and somehow wield her to blast enemies. Bijou also helped by throwing rocks. According to a tweet made before her debut, she isn't worried about being "yeeted" because she can fly.[63] She speaks Rock language. She is also trying to learn Thai and Japanese. Her age is unknown. It was cut off in her debut stream, so it is only known that it begins with a 1. According to Nerissa, Bijou is older than her.[64] If Nerissa was imprisoned in The Cell for 9,000 years,[65] the 1 could indicate Bijou is at least 10,000 years old. She is a gem girl, formed from human emotions. She is easily affected by human emotions, and became a VTuber partly to interact with humans from a safe distance.[12] She has the ability to inspire greed in others. When fans are in pebble form, it helps to protect them from this.[12] It is reminiscent of Andvaranaut, the priceless ring of Norse mythology which inspired greed in all who saw it, and which was the inspiration of the One Ring of Tolkien's stories. She has a form called Ascended Biboo. When she becomes angry and overwhelmed with emotions, she cracks and becomes an emotionless being that can control the emotions of beings around her, including gods.[66][67] Her evil doppelganger is named Oobib the Evil. It originates in a stream where Bijou appeared in a box titled "LIVE BIBOO REACTION," but when it was flipped horizonally, Nerissa read it as "OOBIB EVIL."[68] She has stated that she sometimes eats her fans, however they magically respawn later. Her floating crystals can transform into any weapon she desires. She confirmed that her katana is made from those crystals. Her shoes are often joked to be candy because of the crystals covering them. Although Bijou made the shoes out of her own body, they can be taken off like normal shoes.[69] Her "candy feet" are sometimes depicted as making "tink tink" sounds when she walks, although she can suppress teh ability.[70] A good overview of the feet situation appears in the clip Koseki Bijou's "Candy Feet" entire saga in 4 minutes.[71]

Likes and dislikes: She likes games, small spaces, interactive food, pretty drinks, and coffee. Her favorite possession is her coffee machine. She is particularly fond of raspberry mochas.[12] Her favorite music is Utada Hikaru, Vocaloid, lo-fi, and video game OSTs. Her favorite anime and manga are Puella Magi Madoka Magica, Houseki no Kuni, Clannad, Nagi no Asukara, Studio Ghibli, and Mob Psycho 100. Her favorite games are FromSoft/Souls games, Animal Crossing, Splatoon, Hollow Knight, Undertale, Tales of Symphonia, Kingdom Hearts, Nier Automata, Pokémon, practically all Nintendo games, Apex Legends, and MMOs. She dislikes pickaxes. However she deleted her original dislike list: mushrooms (except Enoki), bees, loud sudden noises and scary noises.[72] She plans to stream challenge content, long streams, Bijou themed creative streams, learning streams, trying new things, and community bonding and interaction. Her goals are to appear in a video game, to build a community of millions of Pebbles, to have a voice acting role, to have her senpais notice her and collab with every hololive member at least once, to see someone cosplay as her, and to perform an original song on stage. Her favorite hololive song is Houshou Marine's I'm Your Treasure Box and Ceres Fauna's Let Me Stay Here.[73]

Miscellaneous: At 140 cm (4'7"), she is the shortest member of hololive English at time of debut, defeating previous record-holder Gawr Gura by 1 cm. However, she is still taller than Japanese member La+ Darknesss, at 139 cm. Her emoji is a moai head. It refers to a type of stone statue once built by the inhabitants of the island of Rapa Nui, also known as Easter Island.[74] This was punned on in the title of her debut stream, "Moai Moai Kyun~!" To date, she has started nearly every solo stream in her Moai form (one exception being the first Elden Ring stream), and will only properly show herself with the command "Kira Kira Koseki!", which then shows her Henshin animation done by harutimu. In some collabs, such as with Mori Calliope, her guests seem to get stuck inside the Moai head with her, and will also do their own Henshin animation to come out.[75] She shares the same character designer with Wataame Yume of MUSUBIME, Kanna Yanagi of PixelLink and Yukime Lumi of Specialite. Her illustrator, Kitada Mo, previously drew Hakui Koyori's 2023 birthday merch. She speaks some Thai, a language spoken by her mother.[76] Referencing her lore, in her default Live2D outfit the large crystal array on her chest changes color in conjunction with her facial expressions, ranging from blue when sad, to a vibrant rainbow color when happy. She originally intended for her art tag to be #bijouweled (as a pun on the word "bejeweled"), but decided to keep it as #bijouwled because she thought the typo represented her more accurately as a person.[19] She is a night owl, and usually wakes up after noon. She often wakes up only ten minutes before the stream. She also doesn't eat before or during streams.[12] For her audition into hololive, Bijou created a modded version of Undertale that replaced Sans' sprite, lines, sounds, and attacks with Calli and Deadbeat-themed ones, with the Calli artwork drawn by her. She then played and beat this modded Undertale boss fight in one try in front of the audition staff, and later replicated this feat in a collab with Calli herself.[75] An ongoing joke is to depict Bijou mispronouncing a hard G as a letter J. This began in a Legend of Zelda: Tears of the Kingdom playthrough where it was discovered that she had always mispronounced Gerudo as "Jerudo," and Ganondorf as "Janundorf."[77][78] As a parody of FUWAMOCO's catchphrase "Bau bau," Bijou developed a catchphrase, "Rock rock!" An ongoing joke is that her laugh sounds like a window squeegee. Clippers will often add in a graphic of a window squeegee when she laughs. This is similar to Usada Pekora, whose laugh is annotated by arrows used to denote rising tone. Bijou infamously wrote a hololive Advent themed parody of a 2023 meme song Gyatt for the Rizzler: "Sticking out your gyatt for Nerizzler / You're so Bau Bau / You're so Biboo Tax / I just wanna be your Shiori."[79] She has a cat, named John Cat.[80] She discovered that she has a talent for impersonating Ina, when she uses a voice changer to pitch her voice down. The name "81800" for her third 2D costume is derived from the numerical spelling of the name "BIBOO."[81]

External links: Media: Koseki Bijou Ch. hololive-EN - YouTube channel kosekibijou - Twitch channel Koseki Bijou's corporate profile on hololive.hololivepro.com @kosekibijou - Twitter account @kosekibijou - TikTok account

Hashtags: #LIVEseki - Stream #bijouwled - Fan art #LMOAI - Memes #pebblesona - Pebble Persona tag

Statistics: kosekibijou - TwitchTracker stats kosekibijou - SullyGnome Twitch stats kosekibijou - Social Blade Twitch stats Koseki Bijou Ch. hololive-EN - Social Blade YouTube stats Koseki Bijou Ch. hololive-EN - Playboard YouTube stats

(Note: This character is above 18+)

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