Tabun, Dewanakereba Yokatta Usotsuki na Kimi ni

Koyo Ito works at a law firm while studying to pass his examinations to become a judicial scrivener. One day while out drinking with his friend, Morio, he meets a mysterious and alluring girl in college who goes by the name "Nana." Koyo, who for some reason or another had already given up on dating, is met with a suggestion by Nana that the two "go on a date." Right as a spark is ignited between the two, Koyo's co-worker, Minegishi, begins showing interest in Koyo, which leads to the breaking down of Koyo's everyday life. (Source: MangaPlaza)