As introverted colleagues at a travel agency in Tokyo, Takuya Oohara and Rika Honjouji both cherish their happily single lives. After work, home is where they feel most at ease: Takuya unwinds with his cat, while Rika studies various maps. However, an uncertain future looms over their treasured tranquility when their company plans to open a branch office in Alaska within one year and transfer an unmarried employee there.

During a day off, Takuya and Rika accidentally meet and, despite never having spoken before, open up to each other about their relocation fears. Feeling encouraged by Takuya facing the same predicament, Rika suddenly proposes a daring solution—to pretend to be engaged for 365 days. Takuya accepts, but little do the two know that the path to marriage may, in many ways, change forever the very lifestyles they struggle to preserve.