Tenjiku is a long-haired muscular man.
Tenjiku doesn't usually talk much. Amame describes him as "an idiot, but skilled".
He and his sister, Amame, were born in a clan of hitmans called "The Rakshasa" that existed for over 300 years. When they were young, their parents died in an aerial bombing which led his sister to seek help from the ARES Board Chairman. Since then, the siblings worked for the him.
Along with his sister, he was assigned to find the Professor. While Amame stabbed him through the chest. Tenjiku assisted to create a large explosion. Many people thought that the Professor has been killed. However, the siblings keept him alive and imprisoned him within Ares' office.
Later in part 2, they are assigned to find the Ark and pursue Minami Azuma who is carrying the Ark with her. The siblings invade the ESP Liberation Front, but they failed. The siblings gather alongside the other ARES members. When the ESP Police captures Minami Azuma and Kozuki Kuroi, the siblings also participate to seize them. They almost manage to take Minami, but is interrupted by Rinka Urushiba. However, they manage to capture Kozuki Kuroi. Rhadamanthus later uses his power to command Kozuki to bring the Ark. As such, they manage to obtain the Ark, and acquire the Messiah's power. However, Claudia Kuroi betrays them.
When the Professor escaped from his custody. The siblings and the Chairman warn Rinka Urushiba that they have to handle the Professor. Later, Amame and Tenjiku are assigned to hide. While the Chairman goes to talk with the Professor. The Chairman also tells that if there is any chance, they have to kill the Professor immediately. The Chairman reveals that the one who killed the Professor's wife and comrades is dead over five years ago. They realize that the Professor's illusion starts to fade. However, the Professor suddenly appears behind Tenjiku, and shot him in the head. The Professor claims that his revenge can never be settled. When Amame is overwhelmed and the Chairman gets shot in the stomach. He fires the Professor all of sudden, piercing the Professor's stomach. He somehow survives the headshot, realizing that the situation is extremely complicated, he decides that the only way they can kill the Professor is to create a huge kamikaze explosion. A few seconds before the detonation, he tells Amame to run. While the Chairman and Sukesaburo are clearly seen burned, it's unknown if he manages to kill the Professor and Minami, and whether his sister is able to escape.
Pyrokinesis: Tenjiku has the ability to control and manipulate fire. He is able to shoot flames from his fingers. He has also been shown to be able to create a massive explosion.
Flight: By using his flames, he has also the secondary skill which allows him to fly. When flying, he usually carries Amame on his back.
Detection: He is a part of the Rakshasa. It is stated in the manga that the people of the "Rakshasa" clan don't use their eyes to see but their skin instead. This way, they can detect any enemies with several hundreds of their skin. It's an innate ability from his clan.