(from ebookjapan):
One day, a package arrived for elementary school student Michiru! When she opened it, she found a stuffed dog with a zipper on its tummy... but it turned out to be a "mean dog" with a tummy from another dimension! The mean dog Pecchi tries to make Michiru-chan happy with the weird tools and creatures that come out of his tummy. ......? Fancy gags by a weird dog! And Tik-kun and Tok-kun make an appearance!