Strongest Sage With The Weakest Crest (Manga) Vol 18

A chaos demon with greater power than Zaridias will soon be revived. Such a powerful demon is beyond what Matthias and his friends can handle, but an ancient sword may be able to give them a chance. However, the ancient weapon is sealed in a casket that is guarded by an incredibly powerful elite demon and in order to obtain the weapon, Matty must use himself as bait to distract the demon! Square Enix Manga
(W) Shinkoshoto (A) Kansho & Hyoko, Huuka Kazabana