The King’s stamp was guarded by Riku’s family for generations, until Sonsaku took it. It has great power that enables anyone to be a High Mighty. Wars happen for it.
Rikuson Hakugen, a son of Riku, comes to Sonsaku to work for him. Even though they are enemy, Rikuson still wants to protect the stamp. But, Sonsaku has many enemies. They come, kill him, and took away the stamp. Before that, the stamp gives its power to Rikuson. Now, he would do anything to get it back.
Hanami works on this project.
Btw, it’s also available on anime. I hope watching it will make it easier to understand.