The Sage who returned from another world wants to live quietly

At the age of 15, Saitou was reincarnated as a sage, and he successfully defeated the Demon King in a new world. His victory opened a portal between the foreign land and Japan, and Saitou returned to his homeland with his newfound powers. However, almost 20 years had passed since he left. When he finally reunited with his childhood friend Kanako, who was now a single mother, he discovered that an enemy was threatening her. Thus, the story of a powerful sage seeking a tranquil life in his own country unfolds.