Isekaigaeri no Daikenja-sama wa Soredemo Kossori Kurashiteiru Tsumori desu (Associated Names)

After being transported to another world at age 15, Saitou became a great sage, defeated the demon lord, and safely returned to Japan. Expecting to live a humble life in his hometown, he instead discovered that 19 years had passed. Not to mention after saving his beautiful former classmate and helping yokai, he finds himself…