Kirishima attended Ebizuka Mid 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 upperclassmen dare to go near him.
Kirishima, along with Pon and Mako, would become well known 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 any followers.
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 they find out about Odajima, Kirishima stated that it didn't matter what happens from now on.
At this time, Kirishima considered not going to high school.
When Kirishima, Pon and Gunji arrived to help, Kirishima tells Odajima's brother that Suzuran can kiss his ass 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 saw him walking by, they began to panic in fear. Katsuragi stopped and asked whats going on and looked 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 apologize and run in fear.
It was the first time they met Suzuran's infamous, Genjirou Katsuragi and after talking to him, he saw the appeal of Suzuran. Kirishima decides to join Pon and Mako and go to Suzuran together.
When they enrolled into Suzuran, the Ebizuka Trio win by beating all the freshmen in their class and take over the freshmen. This catches the attention of Izaki Shun, who is now a senior at Suzuran. When Kirishima find out that he isn't the strongest in 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.
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 .
Without any Kurotaki officer knowing, Hiromi was the one responsible for the alliance success after plotting with some students from Kurosaki and Takiya a way to fool their bosses and make them join forces .
During the war against Housen, Hiromi faced their leaders and officials. After beating Kunimoto Tadashi and Machida Katsutoshi, Machida pulled a knife against him but was stopped by Bandou, who took the knife and slashed his face . Hiromi and Bandou then were challenged by the Bitou brothers.
Not much later, he met Katou Hideyoshi and Kobayashi Masanara who said they were going to join Suzuran and fight him after conquering the freshmen . Hideyoshi couldn't conquer the freshmen but was challenged by Hiromi and lost .
Hiromi led the Harumichi Family on the final battle against Snake Heads.
- Hiromi vs. Bandou - Unknown 
- Hiromi vs. Bouya - Lost 
- Hiromi vs. Bandou - Lost, surprise attacked with a steel pipe 
- Hiromi, Mako, Pon vs. Rindaman - Lost 
- Hiromi, Pon vs. Ryuushin - Lost 
- Hiromi, Mako, Pon vs. several Anzai Mitsuhiko's underlings - Won 
- Hiromi, Bandou vs. Machida Katsutoshi, Kikuchi Toshinao, Kunimoto Tadashi - Won 
- Hiromi vs. Tatsuya Bitou - Lost 
- Hiromi vs. Hideyoshi - Won 
- Hiromi vs. Akutsu - Won