30 made Hitori Dattara Issho ni Kurasou tte Itta yo ne?

Synopsis

I thought it was just a careless promise we made while drunk: "If we're both still single by 30, let's live together." In the dead of night, just before her 30th birthday, the suspicious figure who showed up at Tsukiko's house was none other than Sora—the one she made that promise with. It's not exactly glamorous, but their cohabiting life in their thirties turns out to be surprisingly fun—a coming-of-age story at thirty♪ (Source: Takeshobo, translated)