Kigurumi Boueitai

A romantic comedy that revolves around a handsome boy, a beautiful girl, and a person in a stuffed animal costume.

From LuffyNoTomo:

Hakka is a normal girl who's life gets turned around when an invader comes from another planet and large stuffed animals have come to protect the world from invasion. She, among others are chosen to be the guardians and team up with these stuffed animals to save the world! One strange thing other than them being stuffed animals, is that when the guardian and stuffed animal kiss - the stuffed animal turns into a handsome man!