A random love comedy related to Japanese mythology. Tsukuyomi Sasami is a hikikomori girl who keeps watch on her brother Kamiomi with "Onii-chan Kanshi Tool". Sasami has been a little disturbed by the three Yagami sisters who have been charming Kamiomi lately.
She is watching her brother because he has the power to reconstruct the world as he wishes. On Valentine's day, Kamiomi wishes for a chocolate from Sasami
and the world turns into chocolate. In order to stop Kamiomi, Sasami exerts her power a bit and chotto ganbaru.