||This classically trained, all-female 6-piece band creates jazz and samba-inspired battle music. They owe their unique sound to a blend of academic music theory and modern sensibilities. Ink Theory's eclectic approach makes them quite popular with young Inklings and middle-aged Inklings alike.
Ink Theory is an all-female six-piece jazz band. Their songs were added in Version 2.0.0 of Splatoon 2.
- Yōko (ヨーコ ), the trumpet player, is the head of the band, though she holds some jealousy towards her bandmates. She is an Inkling with a mutation that allows her tentacles to have multiple colors, but it rarely proves useful, and she also has a weakness to atmospheric pressure. On rainy days she is said to have a dead face and while she struggles in sunny weather as well, she is a hard worker and always gives a solid performance. She has a sister in high school.
- Karen (カレン), the pianist, is a nautilus who graduated at the top of her class, allowing her to participate in overseas competitions and receive moral support from her bandmates. She appreciates her crisp atmosphere, but worries about her poor vision. She formed Ink Theory after being amazed by the music of Hightide Era.
- Bibi (ビビ), the kazoo player, is an Inkling who graduated from the same music academy as the band's other members. She is closer to the public than the other members of the band, and is renowned for her beauty, often being considered the "flower" of the band. As a result of this, she gets a lot of attention, often being pulled in front of cameras. She is a large spender but has never struggled very much financially.
- Aachin (あーちん), the bassist, is a Hemicentrotus pulcherrimus, a type of sea urchin. She grew up in a strict household with parents who are famous musicians and was a fan of contemporary music but eventually fell in love with classical styles as well. However, she is also romantically inexperienced, often falling for bad people.
- Mayaya (マヤヤ), the percussionist, is a sea anemone who joined Ink Theory after graduating from a music academy. While her professor recommended she become a music instructor herself, she decided she would rather create music. She mainly plays with Ink Theory, but occasionally freelances for other bands.
- Kitamura (きたむら), the drummer, is a sea urchin and the band's mascot. She has a high singing voice and regularly follows new fads. She lives by herself, paying close attention to her curfew.
- According to a Splatoon 2 anniversary Famitsu interview with the developers, in-universe, Ink Theory was inspired by Hightide Era. This connection can be seen in the outfits worn by both bands: Hightide Era wears mainly black with red neckties, and Ink Theory wears mainly black with gold ties.
- Like MURASAKI of Squid Squad and unlike in-game sea urchins Spyke and Murch, Kitamura's face does not appear to be distinguished from the spiny part of her head.
- Ink Theory is the largest band in the Splatoon series, with six members.
- Strangely, in the Valentine's Day artwork, Yōko's hat appears to have actual Japanese kanji, rather than wording in the Inkling language. Specifically, it reads "可憐," which translates to "pretty", while coincidentally also being pronounced "Karen".
- An urchin wearing a bow resembling Kitamura can be seen in the crowd of Pearl's gig in the photo in Marina's chat room. Whether this is Kitamura or a similar-looking character is unknown.
Artwork of Ink Theory for Valentine's Day, 2019.
Names in other languages