Description:

"Welcome to the Kindom'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)

Alternative Titles:

ただの門番、実は最強だと気づかない～貴族の子弟を注意したせいで国から追放されたので、仕事の引継ぎをお願いしますね。ええ、ドラゴンや古代ゴーレムが湧いたりする、ただの下水道掃除です～, Tada no Monban, Jitsu wa Saikyouda to Kidzukanai