Josou Sennen Oukoku

The hero is summoned to a different world. Able to wield a sacred sword and blessed by the goddess. He teams up with heroines to defeat the demon king as that is the only way he can be sent home. But he is soon disappointed when that plan fails. He is told, he can't be sent back until he brings peace to the land. He now has to help forge a peace treaty between the demon tribes and the human kingdom. But each heroine has her own agenda on how the treaty should be written and will do anything to persuade the hero.