Juubei Kakei (筧十兵衛 Kakei Jūbei) is a fictional character in the manga/anime series GetBackers.
The heir to a clan that has served the Fuuchouins since time immemorial, he and Kazuki Fuuchouin were childhood friends. In the Infinity Fortress, he assumes the second post under Kazuki in the legendary gang, Fuuga (however, latest manga chapters does not agree to this statement. It is said that Saizou is the advisor and closer friend to Kazuki, probably because both of them are destined to be Fuuchouin heirs). When Kazuki left Infinity Fortress, Juubei remained, and they eventually met in battle during the IL retrieval, at which point Juubei lost his eyesight. However, in the aftermath of the battle, they were reconciled and have remained close ever since. It is often speculated (both by fans and characters) that the two are lovers, and Ayamine has spoken positively of this idea in his "freetalks". Juubei is also protective of his older sister, Sakura and will come to her defence if she is threatened.
An impossibly serious person (his language reminds one of the samurai of feudal Japan; one of Ban's nicknames for him is "samurai boy"), Juubei often cannot understand the jokes made by others. Even Haruki Emishi, the "king" of bad jokes in the series, repeatedly says that his jokes are at least better than Juubei's. This, along with his relationship with Kazuki, ends up being joked about within the series.
He recovers his eyesight in the arc "Get Back the Lost Time". In this arc, he battles with Ginji. The fight reaches a point when Ginji reverts to his old self, the boy Raitei, and proceeds to destroy everything in his path, including Juubei. However, Juubei is saved by Ban and MakubeX, and the former manages to make Ginji return to his former state. Later, he, together with his sister, Sakura Kakei, and his rival-turned-comrade, Toshiki Uryuu (all remnants of Fuuga), present a last stand at the gate to the Beltline, in order to protect the Getbackers, MakubeX and Kazuki as they enter the threshold of horrors.
After this, Juubei somehow manages to join up with Kazuki as the latter faces off with the Ura-Fuuchouin clan. For a while, his heart is even ripped out of its body by Yohan. In the end, he is saved by Kazuki, who manages to end the feud between his younger brother (Yohan) and the rest of his clan.
Juubei is sometimes called "Tobari no Juubei" (飛針の十兵衛, or "Juubei of the Flying Needles, but in the anime he's called Flying Needles Juubei"), because he fights using long needles. He is also skilled in acupuncture, Shinjutsu (or needle techniques) and understands the flow of chi, for these skills were passed down in his family. By inserting needles into the right pressure points he can turn his arms into steel to protect himself from attacks.
Under dire circumstances, he sometimes resort to using his most secret and forbidden technique, the "Kokushin", "Black Needles" in battle. These needles are made of lodestones and as such, by generating a magnetic field through a "Taichi Stone" (太極石), he could control them better than his "White Needles". However, this increased power comes at a price: his body will take damage while he's generating the field. It's also his excessive use of the stone which caused his blindness in the IL arc. In the "Get Back the Lost Time" arc, he implanted the stone into his body, granting him even greater powers (and the benefit of keeping his hands free). However, the added price is that he can no longer be near anyone, for the stone now generates "radiation", effectively making him a mobile X-ray machine.