A Little Summoner and A Bored God

A Supreme being of The Universe Sits on The Golden Throne Of Heaven,Being Bored to Death. No one in his Vast Empire can Challange Him Anymore.
This is when a little girl from another world summoned Him to help her Defeat Demons that Enslaved her planet.
Ruthless Emperor Harold Who lost his Feelings and Emotions Relearns what It means to Care about someone.
Ruthless Murderer Who only Cared about Battle and Blood has changed.
He will start fighting for an Unreachable Goal - Peace in an entire Universe.