The Strongest Sage with the Weakest Crest

, also simply known as and, is a Japanese light novel series written by Shinkoshoto and illustrated by Huuka Kazabana. It began serialization online in December 2016 on the user-generated novel publishing website Shōsetsuka ni Narō. It was later acquired by SB Creative who published the hardcover volumes since May 2017 under their GA Novel imprint.

A manga adaptation with art by LIVER JAM&POPO has been serialized online since July 2017 via Square Enix's online manga magazine Manga UP!. The manga is licensed in North America by Square Enix.

An anime television series adaptation by J.C.Staff premiered in January 2022.

Plot
In a world of magic, the powers and future of a mage are predetermined at birth through so-called "Marks"—four symbols that categorize a human's aptitude for magic. Lamenting the fact that his mark was considered ill-suited for combat and only useful for magic augmentation, an incredibly skilled sage decided to reincarnate himself for a stronger mark.

Now reborn as the third son of a duke's family named Mathias Hildesheimr, he attains the strongest mark he always desired. Unfortunately, it is also discovered that mankind's knowledge of magic and swordsmanship has drastically deteriorated in this era; only shoddy magic equipment can be sporadically found, while even the most basic spells have been forgotten. To add insult to injury, his current mark, once hailed as the most powerful, is now viewed as the worst.

When Mathias becomes 12 years old, his unrivaled swordsmanship lands him in the Second Royal Academy. Shattering prejudices, he promptly makes ripples in the academy and beyond. However, the former sage uncovers signs of dark forces working in the shadows, and with humanity weaker than ever, it is up to Mathias to thwart their evil plans.