Isekai-gaeri no Daikenja-sama wa Soredemo Kossori Kurashiteiru Tsumori desu

At the age of fifteen, Saito was abruptly whisked away to another world, where he rose to become a powerful Sage and ultimately vanquished the Demon King. Having fulfilled his grand destiny, he safely returned to Japan, eager to leave his heroic past behind and embrace a quiet, unremarkable life in his hometown. However, reality quickly shatters his peaceful dreams when he discovers that nineteen years have passed on Earth during his absence. Now navigating a world that has moved on without him, Saito crosses paths with Madonna, a former classmate who is now raising a child as a single mother. When he steps in to help her out of a dangerous situation, his extraordinary abilities inadvertently draw the attention of the local mafia and other formidable organizations. Despite his desperate desire for anonymity, every attempt to keep a low profile only entangles him further with these powerful factions. As the underworld closes in, the great Sage finds himself trapped in an endless cycle of unwanted conflicts, struggling endlessly to achieve the simple, slow life he fought so hard to earn.