Three classmates who make their living (literally!) by acting as agents of the Z-Loan office and dispatching zombies--Chika Akatsuki, Shito Tachibana, and Michiru Kita--are hot on the trail of an elusive psychopath known as â?œThe Butterfly.â?? But as if serial killers and zombies werenâ?™t enough to worry about, poor Michiruâ?™s barely had a chace to get used to her new digs, her new life, and... Whatâ?™s this? A new member!? Chikaâ?™s friend Shiba joins the teen trio as they solve riddle after riddle and get ever closer to the madmanâ?™s lair.