|SPOILER WARNING: This section contains major spoilers for Yakuza 0.|
Tachibana displays a cool demeanor, and is a seemingly calm and emotionless man. These main characteristics helps him serve as a counterpart to the more fiery Jun. Tetsu in his youth suffered discrimination from others and thus became fearful of others. Moving to Japan, he had no choice but to become a member of the underworld. As he tells to Kiryu, his life was basically use and to be used by others. Only learning that his sister has come to Japan and was still alive did he regain some resemblance of conscience. When he finally learns that Makoto is alive he felt remorseful for the man he had to become to survive in the Japanese underworld.
He wears a three-piece suit, a striped tie, dress pants, and a pair of dress shoes. His hair is neatly slicked back, and his prosthetic right hand is covered in a leather glove.
Being born to a Japanese mother in China, Tetsu's life was one born of discrimination and strife as in his youth he and Xiao Qiao would endure humiliation and insults from their peers for their Japanese heritage. Feeling that there is no place for him in the country, he left early in his youth. Fleeing to Japan to make a new life for himself, unable to find meaningful work, he resorts to crime and quickly became a ruthless criminal with little regard for the morality of others. Soon after he meets Jun Oda, the leader of a small gang after beating him in a fight and they worked together as partners in crime. However learning that his sister is alive he turns to Shintaro Kazama for help, through him he formed Tachibana Real Estate.
Upon learning that Kazama's position is threatened and Kiryu has been exiled from the Yakuza, he was sent to find the distraught man and make him an offer as a real estate agent for Tachibana Estates. Here he reveals that he plans on challenging the Dojima by obtaining the land first before they do. Entrusting his old partner in crime Jun Oda, he eventually discovers the location of the owner of the Empty Lot. After Kiryu's seemingly last stand against Kuze, Tachibana arrives and saves Kiryu and hatches a plan where he offers a cut of their company's income in exchange for Kiryu receiving amnesty until the land is found.
After Kiryu and Makoto returns to Kamurocho, Tachibana reveals his past and the possible fate of the Tojo clan if they do not acquire the land for Kazama. Before they could make their move they are cornered by the Dojima who sends their assassin Lao Gui to eliminate Kiryu. With no options left, Tachibana lets himself be taken into Dojima's custody where they tortured him. Defiantly opposing them even in torture, Yoneda lands a fatal blow that leaves Tachibana lethally wounded before Dojima Lieutenant,Daisaku Kuze could release him.In his dying words he reveals that Sohei was responsible for everything to Kiryu and Nishikiyama and succumb to his fatal wounds and died before even seeing his sister.
The owner of the porn video shop in Osaka tells Kiryu that, before he lost his arm, Tachibana easily defeated Oda and two other thugs when they met, which seems to indicate Tachibana's strength rivals that of Kiryu. Compared to Kiryu, his fighting mainly consists of kicks and grabs.
- Tachibana appears to have lost of most of his kidney's functions, as according to Oda's accounts that he regularly has dialysis in Elder Chen's clinic.
- He admitted to be a terrible driver, despite the fact that he owns a sports car.
- In Yakuza Kiwami, Tachibana is briefly referenced in the substory Man Scout where the interviewer, also named Tachibana, asks Kiryu if he remembers what he introduced himself as at the beginning of the interview. Kiryu remarks that he "could never forget a name like that."