TONIKAWA - FLY ME TO THE MOON - VOLUME 21

Their time together in the mountains is coming to an end and Nasa and his wife Tsukasa are returning to their cozy home. But one thing remains unexplained: the mysterious legacy that Tokiko left behind. Nasa just can't stop thinking about it and so he decides to get to the bottom of the mystery. But even for a super genius like him, Tokiko's riddle is a challenge of the highest order. When his clumsy wife gets in the way, chaos is inevitable!

Source: Cross Cult / Manga Cult