Hana-gumi

Sakota Takefumi and Mutou Renji invited Yaita Ikumi and Ozaki Kenichi to a meeting, Murakawa Katsuhiro showed up too. Sakota and Renji said that they were planning to make Tsukushima Hana their boss, and the others decided to join too, forming the Hana-gumi.
Their first official action was trashing the Jet Black Scorpion after they ganged on Renji. They were helped by Fujishiro Takumi and Yamaguchi Zenjirou on this one.

On the next year, Tetsuwan Tsutomu, Nakamura Ginji, Akaike Yuuji, Aoyama Kouji and Sawaguchi Masaru would join them. As F.B.I. was losing most big shots to Hana-gumi and the faction was growing, Butcher wondered if that was as far as he could go, but he wouldn't let Hana have it easy, as Suzuran was always a hellish place he started a war on Hana-gumi ambushing their members till Hana come to fight Butcher on a one-on-one.

After losing, Butcher wanted to disband the faction to join them, but Hana didn't want it, instead he wanted the F.B.I. to be their allies and lend their strenght when needed, to do so they request Asai Takahiko, an important F.B.I. member held in high regard by Butcher and Fukamachi, to join them and work as a bridge.

The name F.B.I. remained even after Butcher and Fukamachi graduated, and Asai would lead the group that came to be know as Hana-gumi's shadows force.

Yamaguchi Ranmaru, the right-hand of Harada Tokio and second in the Harada Faction also joined Hana-gumi to work as bridge between the factions.

The Hana-gumi would later beat the Amachi Army.

When they got to senior year, the new top freshmen Sajima Yousuke, alongside Moriken, Utagawa Tomori, Nakano Chuuta and Monnai Naoto joined them.
It was clear that the last obstacle to conquer Suzuran was Hanaki Guriko, so Hana decided to challenge him. He lost but Guriko made a speech about Hana that inspired the remaining factions to join under him. Hana became the first Suzuran leader.