Chihiro Sakai is a novelist who is in a slump, and fatigued and disheartened, she heads to a pet store to relieve some stress. There, to her dismay, she finds that she's allergic to the cats that she adores, so another woman at the pet store offers herself as a "pet." Delirious from the fatigue, Chihiro accepts and they head together to her apartment. After collapsing in her bed, Chihiro wakes up to a clean apartment and a warm meal from Nagisa Wataya, the beautiful and peppy woman she took as a "pet"... However, Nagisa has some... interesting quirks...

(Source: MangaDex)