Shijou Saikyou no Daimaou, Murabito A ni Tensei suru

Varvatos reached the peak of magical power until people feared him as a Demon Lord instead of treating him like a person. Hoping for an ordinary life and a genuine friend, he reincarnates three thousand years later as Ard Meteor and deliberately reduces his strength so he will not stand out. His calculation fails because magic has declined so severely that even his weakened power looks extraordinary. Ard enters an academy trying to blend in, but his social instincts are far worse than his magical ability. As descendants, former followers, and consequences from Varvatos's old life reappear, he learns that changing his body and name cannot erase the past. Escaping the loneliness of being strongest requires trust, not merely hiding strength.