The Detective Is Already Dead, Volume 2 (The Detective is Already Dead #6-10)

"I just knew it. When I, Kimihiko Kimizuka, agreed to help Nagisa Natsunagi find her heart donor, I should've realized I was being dragged into something troublesome. Actually, I had an eerily similar feeling four years ago when I met Siesta on that plane. Speaking of which, that was where I first met the old jailbird Bat. I brought Natsunagi to him, hoping he'd be able to identify her donor-but I never expected him to bring up that name again...

And so, having solved my last case, it was time for me to return to my ordinary high school life-or so I thought. But apparently, Natsunagi still has business with me... What kind of trouble will she drag me into next? Family heirlooms? Spoiled idols?"