The Kitten is a kitten in the video game Yandere Simulator. It sits at the back of the school. You can give Riku Soma an image of it as his task, take a image of it to unlock the conversational topic 'cats' for matchmaking, or have Kokona Haruka follow you by it to learn her opinion about cats.
Yandere Simulator Wiki: http://yandere-simulator.wikia.com/wiki/Yandere_Simulator
The Developers Blog: https://yanderedev.wordpress.com/
The Offical Website: https://yanderesimulator.com/