Ari Kojima and Sousuke Fujitani met as students in the same college seminar. They have been dating for four years, but since graduation, it has been difficult for them to spend time with each other. First they were separated by physical distance and long commutes, then by incompatible and irregular work schedules.

Finally, Ari and Sousuke decide to move in together and live in a "de facto relationship" with no immediate plans for marriage. Although the couple is prepared for opposition from their parents, they do not anticipate the inherent challenges of staying together.