Seishu Inui/Relationships

Akane Inui
Akane and Seishu are siblings, but Akane is 5 years older. She and he often spent a lot of time together and appeared very similar. As children their house caught fire and lead to Akane sustaining many physical burns leading her body struggling for life and Seishu a burn across his face. She later died due to her injuries. Leaving her younger brother in the aftermath.

Hajime Kokonoi
Koko and Inupi are childhood friends, they often spent their after school days together alongside his older sister. Koko had a large crush on Akane and when all three were together he often was intrigued with her. During the fire Koko ran into the house and carried Inupi out thinking he was Akane. Akane was later brought out but she sustained 40 million yen worth of injuries which the Inui family couldn't afford. Koko began getting obsessed with money. But he too couldn't save Akane and she succumbed to the burns and died.

But the two childhood friends stay together. They would spend school time together where Koko would often compare him to Akane, even going as far to kissing him. Comparing the two siblings as appearing the same but Akane was prettier. They both joined the Black Dragons together and lead under Taiju to bring the gang back to it's former glory. During the fall of the Black Dragons they joined Toman.

During their time in Toman they were kidnapped by Tenjiku before the fight against them. Tenjiku took Koko, Inupi, and Takemichi hostage and ultimately let Inupi and Takemichi go and recruited Koko to Tenjiku. The separation lead to Inupi freaking out and needing to save Koko which he confides in Takemichi about. Inupi was ready to kill to get Koko back and acted harshly towards Izana and Muncho.

During the battle between the two gangs Koko and Inupi were put against each other. Koko orginally did not want to hurt Inupi recruiting him to Tenjiku instead. Inupi couldn't raise his hand to him, instead telling Koko Akane is dead and how much longer is he going to be infatuated over money and Akane. Ultimately setting Koko free from the grief of Akane and seeing Inupi as Seishu not as Akane.

They later go their separate ways still deeply caring for each other.

During the final battle with the Kanto Manji Gang, they are reunited again and Koko tells Inui that he finally let go of Akane and is ready to “give himself to Inui”.

Shinichiro Sano
Inupi looked up to Shinichiro and his gang, Shin was his hero. He strived to join when he could. As a youngling Inupi would spend time in Shin's bike shop where a lot of the delinquents of the area found a safe haven in. He and Koko transformed it into their base after the passing of Shin. After the fall of the Black Dragons Inupi strives to repair the Black Dragons to honor Shin. He would often stay with Shin.

Izana Kurokawa
Izana and Inupi met when they were kids at Shin's bike shop. Inupi served under Izana as his right hand man during the eight generation of the Black Dragons. He later disliked the way Izana corrupted and changed the dynamic of the gang. When they saw each other at the grave of Shin Inupi got all angry wanting Koko back fearing that he was going to harm him.

Taiju Shiba
After the fall of the Black Dragons Inupi seeked a successor to Shion. He finds Taiju and after being beat up, Taiju took the Leader position and Inupi as his second. They brought the Black Dragons to strength. But after the battle of the Shiba siblings in the church once again the Black Dragons fell and Taiju disappeared.

Takemichi Hanagaki
Takemichi was Inupi Toman captain and friend. He confided in him to save Koko and bring the Black Dragons back to it's glory he gives his life for Takemichi. Serving under him making him the 11th Generation Black Dragons leader.

Ken Ryuguji
After the end of Toman, together Inupi and Draken opened a Bike shop in Shin's memory. They look out for each other and are close. Inui cares and worries a lot about Draken and often expresses his feelings to Takemichi.