Completely shutting out the outside world with a mask!!! One day, Suzu, a gloomy university student with no friends and poor communication skills, loses his one-of-a-kind, precious mascot, "Kappa-chan." While looking around desperately, the one who picked it up and called out to him was the refreshing and handsome partier, Sasamuro Aiji, with flashy girls in tow. Though he wanted to get it back quickly and flee the scene, Aiji deliberately teased him and wouldn't give it back, making Suzu cry.

He managed to get Kappa-chan back, but on top of being touched by the number one type of person he's worst at dealing with, Kappa-chan was damaged, sending him into a depression. The next day, Aiji gets involved with him again by using him as an excuse to run away from his followers. With no concern for his feelings of dislike, Aiji demands his thanks for picking up Kappa-chan. But when he bluntly says to Aiji, "Because a cheery person like you is a land mine!" Aiji suddenly kisses him through his maskー!!!?

The popular, refreshing, handsome guy [cheery] x Small animal type with no friends and poor communication skills [gloomy]. The love between two polar opposites tied together by the mysterious, soft and cute "Kappa-chan."