Explosive Oracle

One day a boy accidentally stumbles upon a shrine that he never thought existed just outside his village. Even though he was living in that village for more than fifteen years. Seeing the strange and gloomy entrance door to the shrine, the boy gulps saliva as he backs up to report this strange shrine to the village chief, however before he could move even a single step an explosion happened. Explosion so big that it could evaporate planets and could create a dent in space itself. The colours that moved out from that explosion could not be described just by mere words and the radiance was so great that it could light up the whole universe. However, that explosion does not happen in the shrine, it happened inside that stray boy, it changed his life in every way he could have possibly imagined. Note:- Mc is semi OP. He will have a Harem but not too big.