The one single goal in life of the Strongest Old Sage is to subjugate the Demon King. In an epic final battle, both of them met their mutual destruction at each other’s hands. However, the Demon King was not completely destroyed! In order to destroy the Demon King once and for all; post-death, the Old Sage trains in the World of Gods and reincarnates as the Apostle of the Gods, Will. In the reincarnated future, the Old Sage had become a legend and his former disciples hold the supreme authority in the world. The disciples had created an organization to oppose the Demon King and an academy to nurture the new generation of Heroes. Thus the Apostle of the Gods, Will (8 year old), enrols into that Academy of Heroes. This is the story of a boy on a mission to save the world through epic battles while enjoying Academy life.

Hiram, the most powerful demon king in history, ruled over all the demon tribes. He defied the Demon God's demand for sacrifices and lost his life after fierce battle. The demon tribe will never defeat Demon God while living under its control. As long as this was the way of this world, there was no way to become the strongest. Five hundred years have passed since then. Hiram was successfully reincarnated as a "human" youth. Although he was said to be the "weakest", he was actually a human with high potential. To kill the Demon God this time, he began adventurous journey... (Source: Square Enix, translated)

Werner, a brilliant and hardworking magic tool researcher at the Empire’s top institution, the Sage’s Academy, suddenly finds himself expelled by a jealous chancellor looking to profit off of Werner’s inventions. But without Werner, the Academy quickly hits a well, and not a single new magic tool could be developed. It turns out Werner’s theories are way too advanced for anyone else to follow! While the academy flounders, Werner attracts attention from all walks of life—from a maiden dragon to a princess. Armed with the strongest spells and magic tools, he’s ready to enjoy a laid-back life of research...surrounded by cute apprentices to boot! Source: Manga UP!