MUSIC

Splatoon's music is composed by Toru Minegishi, Shiho Fujii, and Ryo Nagamatsu, and is diegetic! Which is to say it exists in the universe of the game.
There are different bands with different styles playing the different songs, and sometimes they cover another bands music! Isn't that fun?

bands introduced in Splatoon

HEADLINER: The Squid Sisters

Calamari Inkantion style: electronic j-pop, idol
Squid Squad Splattack! style: punk rock
Chirpy Chips style: chiptune
Hightide Era style: piano rock band with some jazz
Bob Dub loading screen music
DJ Lee shop music
Turquoise October style: mix of chiptune, industrial, electronic and orchestra
DJ Octavio style: electronic dance music

bands introduced in Splatoon 2

HEADLINER: Off the Hook

Ebb and Flow style: pop with electronic and rap
Wet Floor Now or Never style: rock
the Bottom Feeders style: celtic rock
Ink Theory style: jazz with punk and samba
ω-3 (omega 3) style: cello and DJ(?)
Dedf1sh vaporwave and lofi
Diss-Pair style: heavy metal and EDM
SashiMori style: hard rock with hip-hop

bands introduced in Splatoon 3

HEADLINER: Deep Cut

anarchy rainbow style: mix of Brazilian, Indian and Japanese traditional music
C-side style: upbeat rock
Front Roe style: electronic
Damp Socks feat. Off the Hook style: rock
Octoplus style: electronic
Yoko & the Gold Bazookas style: ska
H2Whoa
Riot Act
Free Association