Isekai-gaeri no Daikenja-sama wa Soredemo Kossori Kurashiteiru Tsumori desu
異世界帰りの大賢者様はそれでもこっそり暮らしているつもりです
A man who was transported to a different world at 15 returns to Japan after becoming a Sage and defeating the Demon King. Upon his return, he discovers 19 years have passed. He attempts to live a quiet life in his hometown but becomes entangled in conflict after helping a former classmate who is now a single mother. His peaceful intentions are repeatedly disrupted as he draws the attention of the mafia and other influential organizations.