Domestic Girlfriend (Japanese: ドメスティックな彼女, Hepburn: Domesutikku na Kanojo) is a Japanese manga series written and illustrated by Kei Sasuga. It was serialized in Kodansha's Weekly Shōnen Magazine from April 2014 to June 2020, with its chapters collected in 28 tankōbon volumes. The manga was published digitally in English by Kodansha USA. An anime television series adaptation produced by Diomedéa was broadcast from January to March 2019 on the MBS's Animeism block. Sentai Filmworks has licensed the series in North America and other countries.

Natsuo Fujii is hopelessly in love with his teacher, Hina Tachibana. Trying to move on, he agrees to a mixer. There he meets an odd girl, Rui, who invites him to sneak out. She takes him to her house and asks him to have sex with her. Natsuo, frustrated that his love will not bear fruit anyway, loses his virginity to her. The next day, Natsuo's dad tells him that he wants to remarry and his prospective partner is coming to their house that evening. As the door swings open, Natsuo is taken aback to discover that Tsukiko Tachibana, the woman his father plans to marry, has two daughters: his longtime crush, Hina, and her younger sister, Rui.