Ari Kojima and Sousuke Fujitani crossed paths as students in the same college seminar. They have been dating for four years, but since graduating, it has proven difficult for them to spend time together. Initially, they were kept apart by physical distance and long commutes, and later by incompatible, irregular work schedules. Eventually, Ari and Sousuke decide to move in together and enter a "de facto relationship" with no immediate plans for marriage. While the couple is prepared for opposition from their parents, they do not anticipate the inherent challenges of staying together.