Kappa no Sanpei Gaiden: Fushigina Kame

A brief time before the conclusion of the original rental book series, a series of unexplained disappearances occurs in the village, with several schoolchildren vanishing without a trace. Kanpei uncovers the mystery after finding a strange clay pot in the grass on his way home, leading him to the fate of the missing villagers. This rare manga consists of four chapters that are no longer in print and hard to obtain. The other three chapters, known as gaiden, are titled Kikami-sama, Yuurei no Te, and Yume no Ham Koujou.