Yasuke Matsuda (松田 夜助 Matsuda Yasuke) is one of the main characters in the Danganronpa/Zero novel series.
Yasuke's title is Ultimate Neurologist (超高校級の「神経学者」chō kōkō kyū no “shinkei gakusha"). He was requested by Jin Kirigiri to extract information out of the survivor of the school's incident, Soshun Murasame.
Yasuke was eventually stabbed in the side by Junko Enoshima who had finally been able to regain her memories. Afterwards, she kicked his body until it was a bloody unrecognizable mess.
Yasuke is tall and slender in appearance, with that his face usually wears a 'signature' apathetic gaze. He has long-shoulder length messy black hair and pale blue eyes. Yasuke's attire consists of a half-tucked in dress shirt and a sloppily worn black tie that is adorned with red decals. His lower-half consists of black trousers, a belt, and bathroom slippers.
Yasuke is referred to as a 'sharp-tongued brainiac' by Monokuma's memo in his profile. He is notably sarcastic and witty.
He is quite mean, rude, and sharp-tongued. This can be seen especially towards Ryoko Otonashi, but, in spite of this, he shows some concern towards her on account of her forgetfulness.
He acts unusually anxious around the topic of The Tragedy of Hope's Peak Academy.
In Yasuke's childhood, his mother was diagnosed with an unnamed disease that appeared to have symptoms similar to Alzheimer's disease— causing her to forget who her own son was. His mother's doctors also forbade Yasuke from addressing her as 'mom', or 'mother'.
Her condition eventually led to her unfortunate death, and possibly, Yasuke's rather ambivalent and aloof personality.
Although he claimed that her death made him feel “free”, it is heavily implied that he still harbors a large amount of guilt and grief over her demise, despite it being so long ago. This is shown through his lonely, and sour personality. Her death may also be responsible for his current profession in the field of neurology, due to the bitterness felt on his behalf towards her doctors, who could have done 'better' in his eyes.
Junko and Yasuke have been friends since his childhood. During the time when both of them were in elementary school, Junko began working on a sand sculpture based on the Sagrada Familia church. However, a month later, it was destroyed by an unknown culprit. After seeing her break down in tears and weep for almost a whole day, Yasuke decided to go and search for the perpetrator.
Yasuke's investigation eventually wound up to a dead-end, as he had never found any witnesses. Not being able to find out anything useful discouraged him. While he was sitting on a bench in front of the remains of the sand sculpture, Junko ran up to him with a large smile and whispered in his ear that she was the culprit who destroyed the sculpture all along, asking him to keep it a secret. When asked for a reason, she replied that she did so by accident. Truthfully, she had done this to get Yasuke out of his house, upset that his mother's condition had led him to become more withdrawn than usual.
In the years following the death of Yasuke's mother, Junko became the person that Yasuke felt he could always lean on. She promised to always be there for him, which helped develop his stronger feelings towards her. As a side note, Junko later bluffs that it was her who was responsible for the death of Yasuke's mother, however it's unknown if she was actually responsible or just said this to pit Yasuke further into despair during his final moments.
Yasuke is noted to be overly defendant of Junko, or rather -- her fabricated personality, Ryoko. This is made evident by several situations that concern her, such as him working to keep her in the academy despite her failing grades. It is later on revealed that Yasuke was in fact Junko's accomplice along with Mukuro Ikusaba in orchestrating the events that would eventually lead up to Danganronpa: Trigger Happy Havoc. As Junko had her memories wiped out for the purpose of testing the memory-deletion procedure meant to host Class 78's Mutual Killing Game and Yasuke, in good intention, had attempted to foil her plans by planting fake information in her notebook while she was in her false persona.
Yasuke's plan had unfortunately backfired and he had ended up being stabbed by Junko in a fit of despair after the latter figured out who she truly was. In the end, it was Yasuke's attempt of saving the students and Junko (from herself) which ultimately led to his murder.
Black White - A tied-up Yasuke is transported into a dark hospital. He ends up in the operating room and a group of Monokuma doctors surround him. The red light of the operating room lights up. From the outside, silhouettes of something drill-like can be seen. Almost immediately, the operating room explodes. The explosion is big enough to destroy the entire hospital. Inside the wreckage, a few pieces of paper were found. On them are hand drawn pictures that look like a Monokuma doctor, with a warning that states that he is a fake doctor, as it appears Yasuke died in the explosion. This execution is only shown in the Official Fanbook.
The relationship between Yasuke and Ryoko are explored through the events of Danganronpa/zero, from the beginning of Ryoko's arrival into the lab, Yasuke treats her condescendingly, berates her, and often makes fun of her whenever he has a chance to, labeling her with the nickname 'Ugly'. On the other hand, Ryoko is infatuated with him, and holds a deep liking towards him despite his sharp-tongue. She has a clingy behavior when around him and constantly whines when he's present, he is also the only person she seems to remember clearly.
On the note of her amnesia and treatment, Yasuke is shown to be if not defensive but intensely protective of her; this is shown when one of the old men of the steering committee insult Ryoko for being a 'dunce with no hope of recovery' and reckons her to be a failure, causing Yasuke to respond in contempt, proclaiming the old man to 'shut the fuck up', and that his 'dirty mouth talks too much'.
There are times when Yasuke is shown to warm up towards Ryoko, seen when he visibly gets angry at her for disappearing and forcing him to go out and look for her; only to find her asleep on his bed when he got back into his lab, he proceeds to leave before Yuto Kamishiro arrives and has a talk with Ryoko regarding the incident. When Yasuke returns, he ultimately apologizes for getting angry and attempts to be obscure with his words.
During the untimely end, Yasuke is revealed to have been protecting Junko's alternate identity, Ryoko from herself by planting fake information inside of her notebook. However, this failed miserably when she had fell into a fit of despair and had killed him after realizing who she truly was. The motive for her murder was only the desire to drive herself further into despair by killing one of the two people she loved the most, this included Yasuke and Mukuro who she later kills in the killing game of Class 78.
- “That girl... Even when people make fun of her, she swipes it off because she thinks it has ‘nothing to do with her’. That’s why I have to speak up for her. I won’t be able to live with myself if I don’t.”
- “Shut up already, will you?”
- “This is probably my chance. My chance to protect her.”
(to Ryoko Otonashi)
- “You're also too loud for someone as ugly as you. Speaking of, someone as ugly as you being scared of flying scalpels is weird too.”
- “...Honestly, your brain is like a bottomless bucket.”
- “Who are you going to report me to? The National Japanese Ugly People Association? That kind of organization would be guilty of discrimination just by existing.”
- “I really can't leave you alone for a second, can I...”
- “...You don't often see someone possessing such a superb, brain-intensive talent as you do affected by memory loss. That's why you're such a rare case.”
- “Still, in the future you should talk to an expert about it. But, if you can't do that, come to me… That's all there is to it, right?”
(to Jin Kirigiri )
- “Clarify the truth...? Isn't that a contradiction? Didn't you decide to cover up the incident?”
- “...So who is this student you want me to interrogate?”
- "Yasuke" (夜助) is composed of 夜 - "evening" or "night" and 助 - meaning "help" or "rescue" which most likely refers to the fact that he attempted to save Junko Enoshima from falling into despair and attempted to prevent the Mutual Killing Game of Class 78.
- "Matsuda" (松田) means "rice field of pine".
- He is one of the people who helped in the creation of the Neo World Program, along with Chihiro Fujisaki and the Ultimate Therapist.
- According to dialogue between the two, Ryoko had bugged Yasuke to watch the movie Home Alone starring Macaulay Culkin for some time, yet always mistakenly referred to him as "Wacooly Culkin".