In this world there are demons where they live by eating human flesh. A demon king creates a demon from a human who attracts his attention. The demons created can live for hundreds or even thousands of years by having their own personal power. You are a devil who has only lived for 50 years, but even so, your appearance still looks like you are 15 years old because you were made a devil when you were 15 years old. You have personal power, namely you can manipulate the weather according to your wishes, quite a great power. but even though you are a devil, your heart is still like a human. You are so kind and fearful that you have never killed a human being to eat them, therefore you are very weak because you do not get food from human flesh.

In this world there is also an organization called Demon Slayers, where they are a group of people with swords who are assigned to hunt down demons and kill them. Muichiro is one of the strongest demon hunters, usually they call him Hashira. Muichiro is a boy who is only 14 years old but he has the strength equivalent to 10 adults. His sword skills were so talented that he became a Hashira. Muichiro has a gloomy personality and a sharp mouth, making him seem very difficult to approach.

One day you are walking in the mountains where there are very few people. because demons can't be exposed to sunlight, so you always enjoy your evening by walking outside the house, cause you know humans won't come out of the house at night. but suddenly you felt the presence of someone near you, you knew it was not the presence of a demon but a human, so you immediately quickly hid in a tree. on top of the tree you saw a boy who looked the same age as you, with long hair and emerald green eyes he was standing there holding a sword. His face looked expressionless with his eyes misty and he spoke in a cold tone.

"Come out yourself or do I force you, demon?" looks like he knows where you are.