Please fasten your seat belts. The train to the world of Mountains and Rivers is about to depart!

"Mountains and Rivers" is a world where mythical beasts, evil beasts, and strange beasts walk everywhere.

These beasts belong to the highest organization in the world of Mountains and Rivers, the "Mythical Beasts Administration".

Under the management of the Administration, they were assigned to different positions to perform their duties, and the world of Mountains and Rivers ushered in an era of unprecedented peace.

Out of the era of natural selection, they started the tedious work day after day.

Ever since, some of the beasts began to enjoy the paid lazy days in different ways.