Demon Against the Door

The adventure begins when the protagonist enters the world of monsters. After dueling with various card masters, the protagonist slowly learns many methods of using monsters and also knows how to quickly summon monsters. There is also an uncle who teaches the protagonist how to use monsters. He seems to be unable to move, so he calls me brother. This is written around monsters. This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.