"Welcome to the Kingdom's capital, Glendia!"

The gatekeeper, who greets every visitor to the royal city of Glendia, is very...... ordinary. One day, the gatekeeper interfered with some unruly adventurers, and he was fired from his job, No one cared about him leave the city. But because he had been fighting against the super-powerful monsters lurking in the sewers of the city, he had become incredibly powerful. Unaware of this, the gatekeeper sets off to find work in the countryside. He gets himself a cute apprentice, and the local people depend on him, but he is continuously amazed at all of the powerful acts that (he thinks) are beyond his abilities. Misunderstanding leads to more misunderstanding, and the gatekeeper becomes a hero without being aware of it.

I'm just a gatekeeper.......

(Source: Hifumi Shobo, translated)