Hiroshi is friend to Sai. He like to call Sai boss
Hiroshi is a friend to Sai Akuto. On Sai's first day at school when he was prclaimed to be the future Demon Lord he was the first person to think he was an okay person. Hirsohi sees Sai as a person to look up to and even though it somethings gets him beat up he is always there for him.
When Hirshi and the others went to Hirsohi's home island he gained the immortal blade turning him into the hero brave.