Manga by author Haruhara Robinson - Status ongoing

The class representative, Saeki, uses an array of tactics to sleep during class. Tokimiya, the boy sitting next to her, tends to observe her different tactics and while doing so his interest begins to shift...In other words, Saeki wants to sleep.

Long time ago, there lived an evil being who reigned over the world through fear, called Satan Rchimedes. He invaded the human world with his many demon underlings, spreading madness and chaos everywhere. One thousand years ago, this menace was sealed by the hero Creation, and peace returned to the world. Now a hole has opened up and the demons are running amok. It's up to the descendants of the hero to kill the demon king.