Detective Is Already Dead, Vol. 3 (manga)

Due to my penchant for getting dragged into things, I, Kimihiko Kimizuka,an ordinary high-school student, suddenly was asked to protect national idolYui Saikawa's Threebillion-yen sapphire!? When there's a detective, there'salways a case, and so, another case begins for me and Siesta's heart'srecipient, Nagisa Natsunagi!