Jukokuin no Tensei Boukensha

Jukokuin no Tensei Boukensha is a Manga/Manhwa/Manhua in (English/Raw) language, Action series, english chapters have been translated and you can read them here. You are reading chapters on www.mgeko.com fastest updating comic site. The Summary is

The great sage, Grameos, tired of his current life as a famous mage, decided to reincarnate as a young boy 200 years in the future. Before reincarnating, he places two magic restraint seals on his hands, so that he can hide his enormous magical power after he is reborn.

His motto for the next life is "Hide my powers, don't stand out, and be free".