He's overpowered for sure, but only at night. Well, let's see how long that handicap lasts. At the rate he gains power he'll probably overcome this problem very soon.
So princesses who are in the line of succession lose their names? That's... an interesting choice. I don't get the logic, but I hope it'll get explained. Now that they describe the Rising Sun kingdom as a seemingly matriarchal country formed by the witch of an ancient hero party, I'm going to expect the leader to be the Queen and not the King we saw when Inori was summoned.
I had this gripe for MobSeka that went out of its way to depict an oppressive matriarchy, but for some inexplicable reason the country was still led by a king and a ducal house was led by a duke and not a duchess...