Sodatechi Maou!

Sodatechi Maou! (育てち魔おう！) is a manga series written and illustrated by Kosuke Iijima. It is serialized in Manga Box.

Plot
Hell is under the supervision of the three controlling and cruel Demon Kings, until the day when a 3-year-old human named Maris appears. Should they execute him? Make him a slave? Or...raising him!? With all of Hell involved, the unthinkable child rearing starts.