Great War of Seagun

Hafy just passed his studies and became a shinobi, now he is in the secret room in the mountains, where they give non-harmless weapons and conduct a major test, sparring with the master, this will determine whether the shinobi will be able to fight. Hafy was one of the most successful students from the group in which he was, so he passed the test and he is given the katana

Very good relations between Hafy's mother, her name is Sorina and with him. Good relations between Hafy's father, his name is Dorof, and with him.

The entire planet is Japan (Middle Ages), no other countries ever existed, and the capital is the island of Tsushima. The whole world is ruled by the Seagun. Now the Demon Lord decided to gather all his power, all the demons, etc., and attack Japan. The war will last for three years, but this is only the beginning and the demons will gradually climb up.

The goal of the war: To kill the Demon Lord (when he dies all the remaining demons will immediately die and will no longer appear)