Anata to Senya Ichiya

Ooizumi Sonoko is a highly efficient office worker who has no interest in romantic relationships. After a night of drinking, she wakes up the next morning with a man she finds attractive in bed with her. What was intended as a one-time encounter turns complicated when she discovers he is her new section chief. The story is presented in volumes 2 through 5 of Oboretai, with the initial three chapters appearing in volume 2.