Plot

The slime created by the boy Kotarou can transform into a super beautiful girl. Kotarou is constantly getting pushed around by Puniru's freewheeling antics. It's a joyful and exciting life every day.

The story of Puniru wa Kawaii Slime follows the daily adventures of Kotaro, a young boy, and Puniru, the slime he created when he was in elementary school. For the last seven years, Kotaro and Puniro have been great friends, but now that he's a second year student at junior high, Kotaro has discovered that Puniro can take on the shape of a beautiful and free-spirited girl, and her wild behavior causes him no end of trouble.—Crunchyroll News

This is the story of Puniru the slime and Kotarou, a middle school student, until they cease being friends... Kotarou Kawaii is a second-year middle school boy. When he was in elementary school, a slime he created came to life, and for the past seven years, he has been spending time with the slime named Puniru as his "friend." However, there is one problem for Kotarou... Over the seven years, both have grown significantly, and Puniru has transformed into an incredibly beautiful girl. Besides her beautiful appearance, Puniru freely transforms into various cute forms as a slime, causing Kotarou to be both excited and bewildered by her carefree behavior every time. Will Puniru and Kotarou be able to continue spending time together as "friends" despite these challenging days ahead?—Official Website