Solo Shinkan no VRMMO Boukenki: Doko kara Mite mo Berserker desu Hontou ni Arigatou Gozaimashita

Ryuu Shinjou is a student who is invited (forced) by his best friend to enter the world of virtual and online role-playing games (VRMMORPG).
During the game and when choosing his class, Ryuu decides to become a "priest," through which he can regain his health through magic and thus play alone. However, his playing style is far from what you would call a "normal priest." It is time to learn the story from Ryuu, the priest who instills terror into anyone who dares to stand in his way.
(Source: Shousetsuka ni Narou, translated)