Marina - Unsure Idol

Marina is an Octoling that appears to be taller and more curvaceous than most Inklings and Octolings. She has dark brown skin, teal eyes with reddish-pink horizontal pupils (which real-life octopuses have) in the shape of an infinity symbol and two eyelashes each, and dark brown tentacles with teal tips that can also change completely to one color; they are kept very long, arriving past her waist. She also has dark teal eyebrows that are constantly downturned in a "worried" expression, a teal gradient on her fingers, and a beauty mark at the left of her lips. Like Pearl, and unlike other Octolings, her sharp teeth are in the center on both the top and bottom, instead of being asymmetrical. She has also stated that she has multiple hearts, like how real-life octopuses do.

Her outfit consists of a sleeveless, high-collared black top that bares her midriff, showing a teal navel piercing. It has a large, mostly undone silver zipper with an infinity symbol-shaped hole resembling the pupils of her eyes. She has black puffy shorts with a diagonal waistline and slanted grooves that light up in sync with the music; under them are teal tights and black boots with big undone silver zippers with 8-shaped holes like the one on her top. She wears large black headphones with teal rings on the sides of them, covering her ears, and black fingerless gloves. According to her Inkopolis News dialogue, this outfit and Pearl's matching one were designed by a graduate of Inkblot Art Academy. As seen in Splatfest artwork and Marina's Dev Diaries, she also occasionally wears glasses. During Splatfests, the teal on her design changes to match the color of the team she chose, except for her eyebrows.

Marina is more reserved than her bandmate Pearl. She speaks in a sweet, gentle manner, but can get very sassy in response to others teasing her. She is more sentimental and tender-hearted than Pearl, and has been known to break down crying in public when sufficiently touched. Despite her shyness, she does not appear to be concerned about expressing herself. She is forgetful[ and has been observed to forget the news she and Pearl are broadcasting. Her timidity shows when she sees an Inkling watching her through the window; when she notices them, she smiles awkwardly and waves. This behavior likely comes from the fact that many believe her to be an Inkling even though she learned the Inkling language recently and that she looks very different from the Inklings; her Octoling-like appearance was said to simply be a new fashion trend before Agent 8 came to Inkopolis Square. Early in Splatoon 2, international versions characterized Marina as being much more sarcastic and frequently delivering lighthearted jabs toward Pearl's character flaws, similar to Marie; this would be greatly toned down in the following updates. Octo Expansion would later hint this discrepancy is due to Marina wanting to disguise her inner lack of self-confidence, and in Splatoon 3: Side Order her international persona matches her Japanese one.

Marina is known to be very technologically skilled, with Pearl describing her as being "too smart for her own good" in the Octo Expansion. This is demonstrated with the Shifty Stations, a series of stages created by Marina for Splatfests using advanced Octarian technology, with the mechanics from Octo Canyon appearing in them, as well as floating rocks. She is also capable of hacking Kamabo Corporation, allowing Agent 8 to pass a test using the data collected from their previous attempts, and can hack their CQ-80 device to show her chat room or release a distress signal. In the final battle of the Octo Expansion, she can use her laptop to analyze the NILS Statue in a few seconds, learning about the strength of its cannon and its use of sunlight to charge up power. In Side Order, Marina is the creator of the Memverse, a virtual reality setting with which she hopes to save sanitized Octolings like Acht by rejoining the memories stored in mem cakes with their souls; throughout the campaign, she is able to hack into the Memverse's code and provide buffs for Eight and the Pearl Drone. She is portrayed as being obsessed with the machinery found in various stages, such as Sturgeon Shipyard, Port Mackerel, and the bucketwheel excavator in Piranha Pit. She often utilizes similar machinery in the Shifty Station layouts she designs. While she does not like being considered a "nerd" in this regard in Splatoon 2, she seems to have embraced the identity by the time of Side Order. Marina is a childhood friend of Acht, with the two having gone to the same engineering school in the Octarian world.

Marina also owns a keytar with Squid Sisters and Off the Hook decals on the neck, which she can be seen playing during live performances of Muck Warfare and Anarchy Rainbow, and in-game during Splatfests in Splatoon 3 when performing We're So Back; her laptop is decorated similarly. Similarly, she plays the piano while touring with Damp Socks. She is a fan of shōjo manga, with her naming the Shifty Stations after them in the Japanese version and practicing crosshatching in secrecy, and can draw. Her drawings are seen in Octo Expansion before the fight against Tartar as portraits of Agent 8 and Pearl, and seen again after she is rescued in Side Order.