Open it and you will see that it is not a book for children! There is a Playstation software inside! Weird, isn't it?
Koguma-Chan no Daibouken is one of the 3 Sunmark's educational softwares.
From the subtitle "EQ開発エデュテインメント" (EQ Kaihatsu Edutainment), it seems to be aimed at enhancing hearing skills.
I don't know the details on how it was distributed, except that it was out of the commercial circuit.