I Got a Job in Another World to Become a Mercenary

On the brink of despair, a young man on the verge of ending his life encounters a mysterious old man who offers him a chance to change his fate. Transported to a fantastical world, he is tasked with guarding a mystical gate that separates realms.

Sh*t, why is it so hard to write a synopsis? Just read it and tell me what you think.