Ryuuji Kousei

Ryuuji was Yuki's father and a close friend of both Reiji and Hyoudou. He had a large sleeve tattoo of a dragon on his upper right arm. He was connected to the Kawaguchi family from a young age and was childhood friends with Reiji. Sanada gave Ryuu the opportunity to work as an apprentice of a tattoo artist employed by the Kawaguchi family. Because of this, Ryuu became deeply connected to the yakuza, and Ryuu felt he owed a debt to Sanada. After Sanada is killed he tries to save Reiji and Hisako from Doumoto, but was only 17 at the time and had no way to help. After the Kawaguchi family is dissolved it's unclear what happens to Ryuu, though somehow he ends up taking care of Ashiei. He meets Tsubaki through Ashiei and the two fall in love. At some point he meets Hyoudou and the two become friends. He continues to work as a tattoo artist for the yakuza, usually taking trips to work on clients. Eight years after Sanada is killed, when he is 25, Ryuu runs into Reiji again; Yuki is 4 at the time. Around the same time, Ashiei find Ryuu and his family. Ryuu assures Tsubaki that Ashiei is no threat to the family and leaves for a work trip immediately afterward. He disappears for a month and presumably is killed in that time.