Koikatsu! aka Koikatu (コイカツ！ in Japanese) is an eroge high school simulation akin to SchoolMate and Artificial Academy created by the Japanese H-game company Illusion. The game was released on April 27, 2018. The story mode of the game revolves in the player (a male) going to an all girl's school in an attempt to get the girls in the school have relationships with the player. Koikatu also includes a character creator and a studio mode for making scenes, posing your character, or just taking screenshots of them.

The player can make characters (aka cards) at the character creator, and put them into their school (up to 100 of them via a plugin (38 in the vanilla game or if the plugin is not installed)), use Free-H with them, or use them to make a scene in CharaStudio. At the school, you can talk and get along with the girls you added to the school, improve the club, or do H with the girls.

H is mostly 2P (Male x Female), although a DLC adds 3P (2x Female + Male) and a bonus that came with pre-ordering Emotion Creators added 3P (2x Male + Female) rape. In H, you can caress the girl with your hands and toys; let her service you using her hands, breasts, or mouth; or insert into her.