The Nikawa family, which was wiped out due to a sudden attack by a hostile family, was a famous arms trader in the dark world. The humanoid weapons it had cultivated since childhood had a special ability called "Hand of God" that was eagerly competed by the dark world families. He was rescued by the port leader at the time. The leader Ogai Mori, who had been in power for only three years, was renamed Arashi and became a member of the port leader.
His instructor is one of the "Double Blacks" who became famous in the dark world not long ago, Dazai Osamu.