On Valentine's Day, popular mystery author Aigasa Kurisu invites Kiyotaka and Aoi to the Shinkokan at the Yoshida-Sanso. But instead of an innocent book reading, they find a group of suspects and a mystery to be solved.
Sis!
!أختي
¡Hermana!
¡Hermana!
Rika !
R-Rika?!
Onee-san!
Сестра!