Ryokutou

After the demise of the demon lord, the remaining members of the demon race decide to repurpose the left over dungeons for commercial use where people can "immerse" themselves in a fun dungeon experience. A young dungeon designer is struggling to understand what makes a dungeon a "catching experience" until she encounters a slime claiming to be the demon lord.

Kageto Ishidou became a beta tester for the VRMMO “Alter World” for rehabilitation purposes. Perhaps due to his beta testing experience, in the full release he gets invited to a monster village, obtains monster skills and items, and gains extraordinary powers beyond common sense!