MTL - Start the Source of Fire and Create a Mechanical Army - Chapter 239

A loner boy, who’s always loved escaping into his RPG world, suddenly finds himself living as one of his game characters. But instead of becoming his favored fighter, he’s in the body of his second avatar—a support mage! Though he’s used to playing both roles, being the mage in real life is a whole new challenge. Now he must rely on his knowledge and skills to navigate this unfamiliar reality and survive as the game's “support.”

Fear breaks the boundaries between dreams and reality, and it is impossible to tell which is reality and which is illusory. When the nightmare really comes, no one can be alone.

This is both a danger and an opportunity.

- Description from novelbuddy

Chi Lang transmigrated to the Middle Ages as a third-rate magician in a third-rate magic academy. His magical aptitude is zero. But he has a good roommate.

His roommate is good-looking.

His roommate is good-natured.

His roommate helped him escape from danger several times.

His roommate never complains.

Chi Lang felt like he liked his roommate a little bit, and then his roommate helped him solve his ‘single’ problem.

It wasn’t until much later that he realized that his roommate was a remarkable figure.

——He was one of the demons sealed by the magician known as the “God of Magic”… And Chi Lang became the one who unlocked the seal of the Demon Lord.

- Description from Novelupdates