The Isekai Returnee is Too OP for the Modern World (Light Novel)

Morishita Daiki became a hero after being summoned to another world. After skillfully striking down the Demon Lord, he returned to Japan. Daiki, with his strength concealed, was living a tranquil day-to-day life. However, apparitions and those with special powers run rampant in this seemingly-normal world. A supernatural school-battle epic rarely seen in the modern era unfolds in the shadows!! A story about an unbelievably strong hero returning to the modern era after his adventures in another world!