Ai-chan

Ai-chan is a 16 year-old petite Japanese 2nd year high school girl who stands at just 149cm and weighs 50kg.

She has well-maintained brown silky hair with a nice smell of shampoo which she styles in a bob cut, with the addition of two braided strands behind her ears. During her middle school days as class representative, Ai-chan had much longer hair that she arranged into two ponytails on either side. She also wore glasses back then and currently only wears them at home. Her eyes are described as light-green and big with long eyelashes. Her skin is fair and flawless. She’s usually not wearing any jewelry and barely any makeup as well.

Her overall body is quite slender with a flat stomach and thin legs and just like her mother and sister, she is quite uncommonly curvy, often getting her a lot of attention, unwanted or not. Her breasts are exceptionally large for someone of her size and age and are the main obsession of several characters throughout the series. Her bust growth is a recurring topic of discussion, showing little to no sign of stopping as she went from H-cup at the start of high school to now filling K-cup bras. This unusual feature gave her the nickname “Ai-chan”, a play-on-words with “Ai” meaning love in Japanese but also with the letter “I” in English, her cup size when she first met Onii-san. From her first day, she’s considered as the bustiest girl in her school and her reputation has even spread to other local schools as well.

Ai-chan is most usually seen wearing her school uniform throughout the series, consisting of a white shirt covered with a black jacket while wearing a navy skirt. During winter, she usually wears a beige sweater and a peacoat. Given her impressive bust, she’s unable to close her jacket and her white shirt is most often drawn with large creases showing how much she strains the fabric of her uniform. This eventually leads to her accidentally popping her buttons that she usually saves as gifts to Onii-san every Monday as offerings. Ai-chan has also been shown to struggle to find fitting bras that aren't too overpriced and to wear the prettiest ones on Mondays just for him. She can also be seen at a local bakery wearing a close-fitting white and blue waitress uniform with a blue apron and skirt that emphasizes a lot of her curves. Ai-chan also wore dozens of different outfits, usually underlining her imposing assets, either intentionally or not.

In the light of her striking appearance, Onii-san described Ai-chan’s looks as “youth taking a corporeal form” while her best friend Volleybu-chan couldn’t help but notice how immensely popular she was with boys in their school as dozens of them have confessed to her. Meanwhile, girls have shown to express mixed feelings of jealousy and fascination towards the busty schoolgirl.

Ai-chan has shown a lot of different aspects of her kind and gentle personality during her high school years. She notably started as a shy, uncertain and self-conscious girl. During her first months, she struggled with making friends at school as girls were too jealous of her while boys kept on confessing to her. Because of the impressions people made of her, she tended to spend time in the classroom reading a book alone and just wanted to fit in. She also had a complex towards her figure, most notably her chest that she tried to hide by slouching over while its impressive growth in contrast to her short height had a tendency to bother her.

However, her loving relationship with Onii-san allowed her to express another part of her personality. Over the course of the months, she has shown a rather playful and mischievous personality that she enjoys to balance with a coy and innocent demeanor. Most notably, she particularly relishes in teasing Onii-san about her body, often pressing her huge bust on him on a regular basis, usually using the congestion of the train as a tacit excuse to do so. The size of her breasts and their growth have become a recurring theme of discussion with Onii-san on almost every Monday. During these days, Ai-chan is shown to be overly confident, proud and assertive towards her body that she likes to emphasize to impress him, a feat she manages to do almost every time. Their relationship is somewhat unbalanced as Onii-san rarely has the strength to resist her teasing attacks and Ai-chan on the other hand is rarely put in a difficult situation and if so, it does not take long for her to take the upper hand again.

This relationship greatly influenced Ai-chan’s whole personality, improving her self-confidence after every Monday. She becomes more and more assertive as the story progresses to the point that she finally accepts her body as it is, most notably by straightening her back. She got comfortable enough with her striking figure to even joke about it with her friends or comment on how boys are crazy about them. This boost of self-esteem greatly helped overcoming her shyness and made her able to bond even with girls that are jealous of her.

Other than that, Ai-chan is also seen as an impressively competent person, capable of arranging the logistics of school ceremonies and festivals and she takes her role as a class representative very seriously. She’s also very mature for her age and usually gives enlightened thoughts to people in need of them. She can also sometimes be aggressive if she’s been fooled, most notably against her best friend Volleybu-chan or her younger sister Imouto-chan who enjoy teasing her.