Shūkurō Tsukishima

is a mysterious individual who is capable of using Fullbring, and the former leader of Xcution.

Appearance
Tsukishima is a tall young man with long dark hair. He wears a long-sleeved collared shirt with suspenders and dark pants. He has a scar across his left eye.

History
Some time ago, Tsukishima was the leader of the group Xcution, he gathered together people with Fullbring abilities in order to find a way for them to erase their powers. He formulated the plan to pass their powers on to a Shinigami Representative, thus forming the group, Xcution. However, once this process began, he had a change of heart and used his abilities to kill the Shinigami and those who had been relieved of their powers. His assumed a new goal, to keep Xcution, with its new leader, away from other Shinigami Representatives.

The Lost Substitute Shinigami arc
While Uryū Ishida is waiting outside of Ichigo Kurosaki's house, he spots Tsukishima standing on a nearby rooftop. Tsukishima leaves, causing Uryū to follow him. Using his speed, Tsukishima is able to catch Uryū off-guard and wound his right shoulder.

Sometime after his attack on Uryū, Tsukishima sends Moe Shishigawara to attack Orihime Inoue, but says that he does not need to do anything, because he believes that Shishigawara will not harm girls. As Shishigawara is about to fight Orihime, Tsukishima arrives and tells Orihime that he was the one who attacked Uryū.

Tsukishima introduces himself to Orihime, but Shishigawara interrupts their conversation, insisting that he will be able to take care of Orihime for him and tries to fight her. Tsukishima tells him to go home, but Shishigawara refuses. Tsukishima closes his book and reminds Shishigawara that he told him that he didn't need to do anything, and asks why he is still there. Shishigawara tells him that he wants to be useful to him. Tsukishima then casually remarks that he lost his page and takes out his bookmark, turning it into a sword. He asks Shishigawara if he minds taking responsibility for his lost page. Upon seeing the sword, Orihime asks him if it is a Zanpakutō. Tsukishima replies that it is not; it is actually his Fullbring, Book of the End. He tells Orihime that she can relax, as he does not plan to harm her at this time; instead, he is going to punish Shishigawara, who cannot follow his orders. Orihime moves herself in front of Shishigawara, which causes Tsukishima to remark that she is good-natured to the point where she does not like seeing even an enemy hurt. Orihime denies that being the reason; she informs him that since he attacked Uryū, she cannot let him leave. He merely replies that her reasoning is boring before turning away from her. When Orihime goes to use her powers, he attacks her from behind and appears to seriously wound her, however, she is shown without any damage moments later.

Powers & Abilities
Enhanced Speed: Tsukishima has remarkable speed; as noted by Uryū, his speed is far above that of a normal Human. Tsukishima is even quick enough to catch Uryū, who is a proficient user in Hirenkyaku, off-guard.

Fullbring

 * Tsukishima's Fullbring is activated by manipulating his bookmark into the shape of a katana.