The Principle of a Philosopher by Eternal Fool "Asley"

Synopsis

When Asley was young, he had dropped from the Magic Academy and was looked down by others. However by chance, he discovered a god medicine and obtained an immortal body. In order to take revenge on the people who made fun of him, he started to work on the research of magic and magical artifacts much different from those developed in the academy, and before he even noticed, 5000 years have passed and he became an ancient magic user. Losing his purpose life, Asley goes out on a journey with his familiar, Pochi, to see the world after 5000 years. With an unexpected turns of events after helping many humans, he is now living at the Magic Academy... How a 5000-year-old with young appearance Asley will live his second life? (Source: Official site)