Kohaku is a rather accident-prone angel who has come to Earth in search of the Angel Master, Hisui. After getting trapped in a tree and attacked by a crow, Kohaku is rescued by Shuuichirou, a young doctor. As a result, Kohaku feels indebted to grant him one wish but finds the kind doctor is satisfied with all aspects of his life. Thus, Kohaku remains with Shuuichirou in hopes of repaying him somehow (subsequently getting in other sticky situations as a result). Kohaku is neither boy or girl. Angels and demons do not have human genders, so referring to Kohaku as "he" or "she" is incorrect. However, the English translation of the manga took liberty with this and assigned Kohaku female pronouns.

Wish spoilers

Kobato spoilers



Drug&Drop spoilers

(Source: Wikipedia)