Sentarō Kotsubaki

is the co-3rd Seat of the Thirteenth Division of the Gotei 13 under Captain Jūshirō Ukitake. He shares the position with Kiyone Kotetsu.

Appearance
Sentarō has dark hair and a short goatee. He wears a customized version of the standard Shinigami shihakushō, wearing a thin white headband and white straps around his shoulders, which are tied in a circle at his back.

Personality
Sentarō, like Kiyone Kotetsu, holds his captain in high regard and tries to impress him in any way possible. Both he and Kiyone frequently get in arguments and fights over their competition to impress their captain. He often speaks in a very loud voice or shouts.

History
Shortly after Rukia Kuchiki joined the 13th Division, a drunken Kiyone and Sentarō eavesdropped on a conversation between her and Kaien Shiba. They applauded Kaien on his words before he asked if they were drunk again. Sentarō told Rukia that he is from Rukongai as well and people talked behind his back about him. Kaien then ordered them back to their posts. Some time after Miyako Shiba's death, Sentarō and Kiyone became the 13th Division's 3rd Seat officers. When Rukia was informed that she was being sent on a mission to the Human World, Kiyone reassured her that she was not being transferred, reminding her of a previous mission to the Human World. When Rukia did not remember this, Sentarō insulted Kiyone. Kiyone and Sentarō then listened as Ukitake talked to Rukia about letting Byakuya know about her mission.

Soul Society arc
After Ichigo, Ganju, and Hanatarō's attempt to rescue Rukia is foiled, Ukitake calls for Sentarō and Kiyone. The pair appear and Ukitake asks why they followed him there when he told them not to come as it was too dangerous. Sentarō comments that it was scary and says that because he respects Ukitake so much, he cannot help following him. Kiyone is annoyed by this, calling it a cheap shot and says that she respects Ukitake more. The pair argue until Ukitake tells Kiyone to contact the Fourth Division so that Ganju's injuries can be treated. The captain tells Sentarō to carry the unconscious Rukia back inside the prison. Sentarō orders Hanatarō to move aside, but he refuses. Sentarō angrily asks if he thinks that he wants to put Rukia in prison and takes Rukia inside, telling her that he is sorry and that he and Ukitake will get her out of prison. Kiyone hears this and complains, saying that she is more concerned about Rukia and that she and Ukitake will get her out. As the two squabble again, Sentarō tells her to contact the Fourth Division, but she insists that she was on her way there anyway.

Later, Sentarō very loudly reads Captain Retsu Unohana a message from Ukitake which asks for clemency in punishing Hanatarō. They listen as Unohana points out that because of his help, the Ryoka did more damage than they would have done alone.

On the morning of Rukia's execution, Sentarō notices the beginning of the release of the Sōkyoku. He states that this is bad and asks Kiyone if the captain is ready. She tells him not to yell for no reason, before yelling for Ukitake. Sentarō criticizes her for shouting, but she ignores him and informs the captain of the news. Ukitake emerges from behind a door, stating that it took him longer than anticipated to remove the seal from the Shihōin Shield. He then tells them that since the Central 46 ruled against stopping Rukia's execution, they have to destroy the Sōkyoku. They pair acknowledge his order. The three of them rush towards the Sōkyoku Hill. They arrive as the Sōkyoku is preparing to make a second attempt at killing Rukia. They witness Ichigo Kurosaki destroy the Sōgyoku's scaffold.

In spite of Sentarō's warning not to, Kiyone tries to go to her injured sister's side. Sentarō' is knocked aside as Suì-Fēng moves to stop Kiyone. After Suì-Fēng is dragged away from them, Unohana ferries Sentarō and the other injured individuals inside Minazuki to the 4th Division to be treated. While Sentarō's and Kiyone are recovering, they both receives Isane Kotetsu's message elaborating on Aizen's betrayal.

Bount Arc (anime only)
Note: Events occurring in this arc are only in the anime and do not constitute canon material.

Arrancar arc
Sentarō, Kiyone, and Orihime Inoue eavesdrop as Rukia requests that Captain Ukitake open the training grounds so that she and Orihime may train for the coming war. When Ukitake notices Orihime, Sentarō grabs her and presents her to the captain, claiming to have brought her to meet him. Kiyone angrily shouts that she in fact was the one who brought Orihime. Sentarō then offers Ukitake another cup of tea, but Kiyone stops him, stating that they agreed to do rock-paper-scissors to determine who would bring the tea. Sentarō replies that he who makes the first move wins. The pair fall silent as Orihime talks to Ukitake and Rukia.

The New Captain Shusūke Amagai arc (anime only)
Note: Events occurring in this arc are only in the anime and do not constitute canon material.

Fake Karakura Town arc
After Aizen is captured, Sentarō, Kiyone and Ukitake eavesdrop on Yamamoto scolding Shunsui, Byakuya and Kenpachi for losing their respective captain haori. Ukitake notes that 10 days have past since the battle, Yamamoto has lost his left arm, but it looks like his stamina has returned, which is a relief as Soul Society still has yet to see a being capable of replacing the man.

Zanpakutō Unknown Tales arc (anime only)
Note: Events occurring in this arc are only in the anime and do not constitute canon material.

Beast Swords arc (anime only)
Note: Events occurring in this arc are only in the anime and do not constitute canon material.

Gotei 13 Invading Army arc (anime only)
Note: Events occurring in this arc are only in the anime and do not constitute canon material.

The Lost Substitute Shinigami arc
Sentarō informs Ukitake that Ichigo has defeated Kūgo Ginjō and that Ichigo is okay.

The Thousand-Year Blood War arc
Sentarō and Kiyone notice the giant pillars of blue flame caused by the Wandenreich incursion. As Sentarō notes that each of the pillars has a great spiritual density, Rukia passes them by. They ask where she is going and Rukia tells them that the enemy is likely at the base of the pillars. After she leaves, Sentarō and Kiyone glance at each other and then head out. He and Kiyone are among the Gotei 13 officers who move out to deal with the Wandenreich

During the Wandenreich's second assault, Sentarō and Kiyone witness the transformation of the Seireitei from within the forest outside of the city's borders. Alerted by the sudden change, both assistants run to a nearby shrine to inform Ukitake about the attack.

The next day, Kiyone and Sentarō follow Ukitake to Kisuke Urahara's laboratory, where they congratulate him on his successful treatment of the wounded 11th Division members. When Sentarō notes Ukitake is the best at healing despite being sick not being something to be proud of, Kiyone angrily berates him for phrasing it this way.

Powers & Abilities
Shunpo: While not seen often, Sentarō showed enough skill in Shunpo to appear immediately to not keep his captain waiting.

Zanpakutō

 * Shikai: Not Yet Revealed
 * Bankai: Not Yet Achieved

Quotes

 * (To Jūshirō Ukitake) "I'm very, very sorry, but I respect captain too much and I couldn't help, but follow captain anywhere he goes."

Navigation
Sentarō Kotsubaki Sentarō Kotsubaki