Yarinaoshi Kizoku no Seijinka Level Up

Selim, heir to a noble house, once made a pact with a demon and became a fiend, only to be slain by the hero. But when he opens his eyes, he finds himself back in time, years before his death. Mysterious words appear before him: "Accumulate virtue and resist the demon's temptation"—a daily quest demanding acts of kindness?! With his healing powers, Selim brings comfort to the townsfolk, earns EXP, and unlocks new abilities. As his deeds of virtue accumulate, so too do the allies who rally to his side.

(Source: Kadokawa, translated)