|Branch of Sin||Unnamed|
|Manga debut||Chapter 42|
She cooperated in the mission to return to Deadman Wonderland once more. Toto Sakigami refers to her as his older sister in the place of his original sister he lost during the earthquake, and she returns to Deadman Wonderland to protect him from harm.
Yosuga is a young, pretty girl. She keeps her hair in two ponytails and has her hair bound by a black and white striped band. Sticking out of the band, at the front, are bangs with longer ones at the sides of her face. Her eyes are dark and big and she has a small cut or scar on her right cheek. She wears normal clothes, a small dress with a black logo imprinted, black sleeves with stripes and wires at the neck opening. She wears black leggings and black, leather shoes. While she was living in G Block, she wore mostly the same type of clothing, but with black and white striped stockings under jean shorts.
The cover of Volume 12, being the first canon depiction of her in color, revealed that she has pink hair, and copper-colored eyes. She is also more pale than Toto when compared side-by-side.
Yosuga was apparently a foster child before she was arrested shortly after the Great Tokyo Earthquake, though the reason for this is unknown. She insists she was framed for the crime, but whether or not this is true isn't clear. When she was in the G-Ward, she was often being bullied by other Deadmen. One time, Toto passes by carrying trophies he won from the Carnival Corpse. She glances at him and he shows no emotion, then he suddenly attacks, killing the bullying Deadmen and takes Yosuga to his room. Yosuga felt depressed, saying there was no reason for her to live, but then he presents to her a plastic gun, which he says she can kill him with and he will rip her to shreds, and that the gun will be her reason for living. Then they end up laughing and play with the plastic gun afterward.
Return to Deadman Wonderland ArcYosuga is first seen when the Deadmen were about to board the Walfisch. She says that they can't defeat Toto with mere numbers, and Idaki Hitara asks if she is an acquittance of Hagire Rinichirō. Yosuga replies that she doesn't know him, and that she "maybe" knows Toto.
She later accompanies Ganta and Senji to search for a Chorus Block. As she was lagging behind, Ganta asks if she's okay and asks her name. Yosuga tells him her name and says that she's not physically strong, but "maybe" mentally. Ganta tells her she didn't have to come to DW, but Yosuga says that she's the same as him. She is also looking for someone she loves (Toto). She goes on by saying that feeling fear is the same as not understanding. This she applies to love: "Because not being able to understand the one you love, is the worst fear of all." Yosuga asks if Ganta is going to kill Shiro because he doesn't understand Shiro. Ganta doesn't answer her.When they found a Chorus Block, Ganta and Senji were working on it while Yosuga was above them, resting. While she was waiting, Hagire comes up to her and recognizes her as Toto's big sister. Yosuga asks what he has done with Toto and Hagire comments on how she has grown since the last time he's seen her. He then says that Toto isn't here anymore. Yosuga notices that Toto's habit of clapping hands is still present and asks Hagire about it. He tells her that he didn't go as far as dealing with Toto's mannerisms. Yosuga doesn't understand and Hagire attacks her, to get her out of the way, because he had to get to Ganta and Senji.
After Toto took Ganta and Senji was defeated, she asks Senji if he's alright, to which he replies that he is a bit dying. She pursues him to return to the ship, but Senji tells her to go on ahead, that he will carry the Chorus Block back after he has rested a while. While on her way back, Yosuga thinks back about Toto.
Senji and Ganta battle Hagire and almost kill him. After being taken to a room to be treated by Game Fowl, she runs away, taking along with her many first aid supplies.
Later she is seen taking care of Hagire, to which Hagire questions her actions to which she replies that she is still his big sister.
Later Toto finds Ganta and the other Deadmen in the Mother Goose System. He attacks them so he can take control of the Wretched Egg. Yosuga appears and protects Toto from several attacks from the Deadmen. Eventually Toto is almost dead from viciously fighting the Deadmen and nearly using up all his blood. Yosuga then begs Rinichiro to give back the real "Toto" and then he impales Yosuga through the head with his branch of sin. After killing Yosuga, Toto gets hit by Ganta's branch of sin and dies.
Before his death, he thinks about Yosuga and then realizes that she was his point for living. It is unclear if both minds of Toto and Rinichiro intersected or if he truly cared about Yosuga at one point or was just delusional.
Branch of Sin: Mitsuzaki is a Deadman, so she has the ability to freely control her blood out of her body.
Branch of Sin: Unnamed Branch: Her personalized Branch of Sin is a shield, though it is unnamed. It is known she was unable to control it very well. Despite this, Mitsuzaki managed to win at least one Carnival Corpse, after which she commented that her Branch of Sin would not let her die, alluding to acting on its own due to her own lack of control. However, by Haggard Absurd, she had apparently learned to control it perfectly, and used it to protect Hagire Rinichirō to great effect, blocking four different Branches of Sin at the same time. It seems to work differently from Rokuro Bundō's Branch of Sin, however, in that her shield requires two hands to form instead of one, and is more rounded in shape like a dome, instead of flat like a disc. Toto Sakigami also appeared to use it offensively at one point, too, using it as a sort of battering ram to slam into Ganta Igarashi and send him flying.
- The cover of Volume 12 was the first ever canon depiction of her in color. The outfit she appears in on the cover was one she was never seen in before in the manga, and is far more revealing than her usual clothes.
- She tends to refer to herself in the third person, much like Shiro does. Interestingly, Yosuga also wanted to be killed by the person she loves.
- Although Toto refers to her as an older sister, Yosuga mentioned that she's 17 and Toto is 18.
|G Ward||Kiyomasa Senji · Minatsuki Takami · Chaplin Sukegawa · Idaki Hitara · Itadaki "Masu" Kazuya · Mitsuzaki Yosuga · Toto Sakigami · Albatross · King Fisher|
|Scar Chain||Ganta Igarashi · Nagi Kengamine · Karako Koshio · Rokuro Bundō · Endō · Ohara · Kosugi · Kōmoto · Miya/Harumi · Wakabayashi · Yamazaki · Akiyama · Ueshima · Miyako · Kazu · Fujiyoshi/Matayoshi · Unnamed Deadman|
|Other||Shiro · Wretched Egg · Chan and En · Hagire Rinichirō · Keigo Ugachi (OVA only)|