Oono Akira, a working adult that can be found anywhere, was transported to a different world while logged into a character known as the "Demon Lord" in a game he manages. There, he meets a girl with a disabled leg and they begin to travel together, but there's no way that others will leave a "demon lord" with such overwhelming strengths alone. While being targeted by countries and saints that are trying to subdue the demon lord, they cause turmoil wherever they go.

Demon lord on the outside, normal person on the inside, a misunderstanding type fantasy!

(Source: Blob Translations, Edited)