A quiet, moonless night.

Tsukishiro Michiru has a dream of being lost inside a mysterious old castle. She meets with five jewels that had taken the form of attractive men. She is ordered by the castle's master. "Choose the jewel you think suits you the best by the night of the next full moon". However, the jewels only have exceedingly harsh personalities that would be called "cruel", "beastly", "sadistic", "scheming", or "yandere"!

As though being guided by something, in the real world she then meets five men that look the same as the jewels she met in the dream world. But completely different from the jewels, these men are refreshing and wonderful. Are they the same person or a different person? If they are the same person, which one is their true self?

While spending the day with the gentle and refreshing men and the nights with the extreme and ill-mannered men, the curtain is opening on days filled with a puzzling "gap"!