Hiromi Kirishima was a student and sophomore at Suzuran All-Boys High when Bouya Harumichi transferred in the School. He initially fought with Harumichi, but later became his friend and occasional confidant.
Middle SchoolEditKirishima attended Ebizuka middle school along with Pon and Mako and would become friends. Kirishima considers them as his brothers and the only time he would smile the way a middle schooler is supposed to was with those two. When Kirishima started middle school, Izaki Shun was the strongest at Ebizuka and was looked up to by Kirishima. Despite being quite mellow and chilled out when he is a senior at Suzuran, Kirishima was considered a dangerous person in middle school and even shaved off his eyebrows so that none of his upper classman dare go near him.
In his second year at Ebizuka, Kirishima, along with Pon and Mako, would become well know around the district as the Ebizuka Trio and were the strongest at Ebizuka. Many of the middle schoolers wanted to join the Ebizuka Trio but they did not take followers.
In his senior year at Ebizuka, Kirishima, along with Pon and Mako, would fight other middle schoolers from outside Ebizuka. They took out Sahara and his guys from Seta mid and Odajima and his guys from 3rd mid. Unknown to the Ebizuka Trio, no one fights with Odajima since he has an older brother from Suzuran that backs him. When finding out about Odajima, Kirishima stated that it didn't matter what happens from now on and that whatever will be, will be. At this time, Kirishima considerd not going to high school. Iwashiro Gunji informs Kirishima and Mako about how Pon is going to go after Odajima by himself.
When Kirishima, Pon and Gunji arrive to help, Kirishima tells Odajima's brother that Suzuran can kiss his arse and that they aren't anything special because they are two or three years older than them. Before engaging them into a fight, Kirishima's speech caught the attention of Genjirou Katsuragi who was walking by. When Odajima's brother and the Suzuran students see him walking by, they begin to panic in fear. Katsuragi stops and asks whats going on and looks at Kirishima, Pon, Mako and Gunji. After looking at them, Katsuragi turns to Odajima's brother and says to him ''Odajima, what the fuck do you think you are doing fighting middle schoolers?!'' Odajima and the rest of the Suzuran students apologise and run in fear. It was the first time they met Suzuran's infamous Genjirou Katsuragi and after talking with him, saw the appeal of Suzuran. Kirishima decides to join Pon and Mako and go to Suzuran together.
When they entered Suzuran, the Ebizuka Trio win beat all the freshmen in their class and take over the first years. This catches the attention of Izaki Shun, who is now a senior at Suzuran. When Kirishima finds that
he isn't the strongest Suzuran, he notes that they will have to face monsters even stronger than Izaki to conquer Suzuran. Kirishima doesn't get the Ebizuka Trio involved with the war between GPS and Serizawa's Army or the war between Suzuran and Housen. Kirishima, Pon and Mako would try and take on the man Katsuragi said was stronger than himself, who they call Rindaman. They were beaten with ease by Rindaman. At the end of their first year, Kirishima, Pon and Mako encounter Hideto Bandou.
In Kirishima's second year, Suzuran is on the verge of being under control by Bandou, with the Ebizuka Trio and Rindaman, all that's in his way. When Harumichi Bouya transfers to Suzuran, Kirishima makes fun of his blonde hair, which results in Bouya throwing his shoe at Kirishima's face. When Bouya follows Akutsu Futoshi to get revenge for Yasuo Yasuda, Kirishima follows after him into the toilets. Before Bouya can fight Akutsu, Kirishima attacks Bouya from behind, but gets knocked out of the toilets from one punch by Bouya.