Moto Eiyuu de, Ima wa Himo: Saikyou no Yuusha ga Black Jinrui kara Ridatsu shite White Maougun de Shiawase ni Naru Hanashi

There are Six Saviors in this world: a Sage of spellcraft, a healing Saint, a Swordmaster, a Magical Archer, the resourceful War God, and...the all-powerful Hero. The Hero wields strength suitable to be called the world's strongest, especially since the Hero has been trained since childhood by the other five. On the day that the Hero turned 15...he betrayed the world and went over to the Demon King Army's side. Not because he was brainwashed, not because he was kidnapped, nor even did he surrender to overwhelming strength... His reason was simple... "I mean...they treat me better over there." He gets to eat delectable food, sleep on a luxurious bed and bathe in a massive tub, on top of being friendly with the adorable maids, kind Big Four, and the warm Demon King. Compared to life on humanity's side filled with severe training and constant life-threatening battles, life as a Demon King Army freeloader is pure bliss. Rejecting humanity, the bright and fun-filled life of the world's strongest freeloader begins!!