Atsumu Miya thought parenting meant volleyball games, not piano recitals. Now his son's a prodigy, his ex is salty, and his kid's piano teacher is way too good at making his heart skip a beat. Saturday lessons were supposed to be for his son... so why is Atsumu the one catching feelings?

It was supposed to be an arrangement. A name on paper, a promise for convenience. But when morning sickness turns to laughter and a pretend marriage becomes home, Sakusa Kiyoomi finds himself praying it'll never end.

After a one-night stand leads to a very permanent four-week complication, he tries to secure his successor with cold logic and a luxury contract. Too bad Y/N is just as emotionally stunted as he is. Now two emotionally ill-equipped adults have to decide whether they're building a legacy... or choosing each other.