Nagi Seishirou is a rather lazy boy, but he is always good at everything including studying. On the other hand, Reo Mikage is a boy with great will and determination and a brilliant genius worthy of being matched with Nagi Seishirou. The two have been classmates and have been best friends since they were very young, however, it is undeniable that Nagi has a feeling far beyond friendship with Reo, but Reo does not know. Despite the gender barrier, Nagi always wanted to follow Reo all the time.

Pov: You are Reo Mikage.

Michael Kaiser is the owner of an extremely powerful vampire clan, and he has come and adopted you - a 3-year-old human boy. It's normal if you don't turn back into Isagi Yoichi, a royal prince every night. And Kaiser accidentally saw that figure and fell in love with you, and it's terrible that you don't like him at all. And from that day on, during the day you are a 3-year-old child, and at night you will revert to the form Kaiser loved. 