Kinyoubi no Toshishita Kareshi

Hirotogawa, who is heartbroken, drunkenly accepts a 'marriage proposal' from his junior colleague Kudo one day. He takes him home and they spend a hot night together, but Hirotogawa, who has no memory of it, has completely forgotten that he agreed to the courtship. The next day, he learns that his application for same-sex partnership with Kudo has been accepted by the company..?