My Wife Challenges Guinness (2006)

Misaki, who wants to date other men even after marriage, is dating 10 men at the same time with Shinji's approval. Misaki is busy managing her schedule, going on business trips with Kanemoto, an office worker, and then with Tachibana, a college student who she became pen pals with, on the way. Misaki and Shinji are a couple who can't get off on each other, no matter how long they spend together.