Kotatsuneko (Kotatsu Cat) is a huge ghost of a cat that froze to death a long time ago after being kicked out by his abusive owners one cold winter. The spirit of the cat decided to go bad and vowed to haunt the people who refused him shelter.

Because he died from cold Kotatsuneko is attracted to warmth. He also had an attachment to kotatsu's because his owners would never let him near one. Kotatsus are toasty little covered tables with a heater underneath to warm your feet. Kotatsuneko was pleasantly surprised to discover the heat that kotatsu emitted.

He's a nice and silent kitty, who just sits with his paws under the table drinking tea and snacking on taiyaki (fish shaped pancakes). He doesn't bother anyone, unless they bother him first. Being a ghost, he has incredible supernatural powers and therefore he's almost unstoppable when he becomes cross; Usually using his brute strength and mastery of sumo wrestling moves to push his weight around. This makes this sumo-kitty the most powerful character in the show (apart from Oyuki).

Partly the character of Kotatsuneko serves as an animal mascot for the show. He adds a humorous element by just sitting there in the background of scenes kind of like those dappya monsters that keep showing up. It wouldn't be a complete show without a goofy looking animal character would it?

Kotatsuneko keeps popping up in the strangest places. Almost as if he has decided to haunt the show itself. Most of the time he's seen hanging around with either Cherry, Jariten or the principal of Tomobiki High School. All other times he just haunts Ataru's room (of course).