Haruka, Riko's mother, gave homework to Riko and the others, who gathered in the attic to talk about creating a detective team. If, without using Kirumin, the group can find out why the old neighborhood dog Gon has lost his appetite, she'll allow them to form the detective club. Riko finds out from Gon's owner Hideaki that Gon lost his energy after going for a walk...
