Akira Oono is an adult working professional who oversees the operation of the MMORPG Infinity Game. After fifteen years, he decides to shut down the servers permanently. However, at midnight, something strange happens, and he finds himself in the body of Hakuto Kunai, a character from his game. As soon as this occurs, he witnesses Greole, a demon, pursuing Aku, a little girl. Although he easily defeats the creature, Hakuto is still worried because he does not recall creating either Aku or Greole. This leads him to question whether he has truly been transported into his own creation's world. To find out more about who or what brought him here, Hakuto decides to embark on a journey with Aku as his guide and companion. Along the way, they will leave destruction in their wake.
The anime is based on Maou-sama, Retry!, the light novel series written by Kurone Kanzaki and illustrated by Kouji Ogata. The series was published by Shousetsuka ni Narou in 2016.