Suzu Shutō (首藤 涼; Shutō Suzu) is one of the main characters of the manga and anime series Akuma no Riddle. She's a former student of the 10th year's Black Class of Myojo Academy who was in a competition with the other students of that class who are trying to kill Haru Ichinose where the reward is anything what that assassin may want. Her desire, should she have won, was to cure her body's disease which prevented her from aging.
Suzu appears as a teenage female with yellow eyes and fair skin. She has light-blue hair that is cut jus above her shoulders. She wears a black headband on top of her head, which separates her bangs from the rest of her hair. In class, she usually wears a black dress shirt with pink plaid sleeve endings and a pink plaid tie. She wears a pink plaid skirt with it, and white sneakers with black stripes.
While in the dorm room, she can be seen wearing a light purple hoodie. For pajamas, she wears a similarly colored set of lavender clothes.
In her past, she wore a bow on her head in place of her headband and also a pink kimono with a green obi. She was also seen holding an umbrella sometimes. Save differences of attire, she is physically the same.
Suzu is generally calm, affable, and knowledgeable in many subjects, likely due to her true age. She speaks in a stereotypically older fashion, using the washi pronoun. Her assassination attempt was one of the most intricate, having required months of planning to create the bomb collar and rig the school's new water park to her making. According to Suzu, she is not confident in her physical strength, thus why she challenges Haru to a game.
As Haru and Tokaku play through her scheme, she also cheers them through, showing no ill will. The way she acts shows that she mainly strives for entertainment and amusement rather than strict success. This is supported by her graceful surrender when her plan fails and Haru lives. In Koakuma no Riddle, she claims that the success of her plan is an answer by Takeo to "live on" despite her sins. Failure would mean she is forgiven and allowed to die. Enjoyment also explains why she indulges in more lackadaisical pursuits while at the academy, using bath salts and seemingly enjoying helping during the Venus Festival.
Suzu shows a good deal of concern for certain members of Black Class, comparatively to other assassins. She shows interest in Kouko's lifestyle initially as a way to observe a young girl, but later remarks that she cannot help but want to alleviate the other's sadness. When Kouko is expelled, Suzu is notably affected. Suzu also gives advice to Kirigaya when the other is conflicted about her love for Chitaru. It is also her who alerts the other classmates to Takechi's true identity as a serial killer.
Despite her smiling demeanor, she hides a lonely side. Suzu admits that she no longer remembers the faces or voices of her friends and family from the past century, and so she holds onto their words, an action she encourages Kouko to do for Irena. Additionally, as Suzu fears the imminent and unpredictable breakdown of her body due to the disease, she is searching for a way to prove she was alive. It is implied she sees this opportunity in Kouko, though it is not clear how.
Suzu was originally born around the time of the Meiji Restoration in Japan. She had a significant other named Takeo. He was one year younger than her and their birthdays were only one day apart. They used to laugh about how people don't stay the same age forever and play shogi together. As Takeo grew older, Suzu realized she stayed the same age. She discovered her body had a special disorder which prevents her from aging. As a result, Takeo got married whilst she remained in a teenager's body. Everyone around her grew old and eventually died while she remained unchanging into the contemporary era.
It is unclear how Suzu came to Myoujou or if she had ever assassinated anyone prior to the events in the Black Class.
Roomed with Kouko, Suzu spends a good deal of time playing shogi with herself and inviting her roommate to the bath. On the first night of Kouko's attempt, she overhears Kouko's conversation with Nio regarding her reward. While Kouko is initially suspicious of her, Suzu assures her that she has no intentions of getting in the way. After Kouko's expulsion, Suzu finds a letter from her roommate telling her to follow her leader. She takes over the role to conduct rollcall, saying Kouko had wished for her to do so.
In Koakuma no Riddle, it is revealed that Kouko found the mystery section of the Myoujou library with Suzu's help. Together, they also find the alleged and elusive book of happiness from the seven mysteries of the school, which turned out to be written by Martin Luther. Kouko asks Suzu why she is helping her and Suzu replies that she has taken a liking to her. Suzu then proceeds to write both their names in the book so that they will be able to achieve happiness, as said by legend. When she suggests taking the book card as a souvenir, Kouko refuses and returns the book and its card to the shelf. This prompts Suzu to comment that Kouko is very reliable.
Suzu plays the role of Juliet's nanny in the class play for the festival. She seems to enjoy her role with amusement. Hitsugi idly discusses with her about the nature of the human heart and the forbidden love between the star-crossed lovers in the play.
She was the sixth assassin to attempt an attack on Haru after sending out a warning letter.
When the Black Class was in Myojo Academy's pool facility as part of a class excursion, she placed a bomb with a timer around Haru's neck, which could only be opened with a 4-digit password that can be deciphered by finding four playing cards hidden within the facility. However, the password on the bomb could've only been wrong to a maximum of 2 times with a total of 3 tries. All this was her plan of making the assassination attempt into a fun game.
While Tokaku and Haru run around looking for the cards, Suzu and the other classmates relax, with Isuke enjoying the struggles of room 1. Sumireko drops a hint on dummy cards, prompting Tokaku to sift through Suzu's deck for missing numbers. However, this clue turned out to be misleading, as Suzu intended for that to be a dummy code, and that wastes one try on the collar.
Despite initial failure and setbacks, Tokaku and Haru manage to find three out of four of the cards. As they search for the last one, Mizorogi arrives to wish Suzu a happy birthday, and Suzu reveals to the class the nature of her disease and her wish to cure it. Tokaku finds the last card, but is trapped in a cage underwater, which forces Haru to sacrifice the card in order to save her roommate. Thus, they are left with only three cards and two attempts to deactivate the bomb before midnight. Isuke ends up wasting one of their attempts by inputting her own lucky number.
On the last attempt to deactivate the bomb, Tokaku eventually figured out that the code was a birthday. Believing it to be Suzu's, she is about to input it, but was stopped by Haru who claimed that she knew what the real number was, Tokaku agrees and enters the password, successfully unlocking the collar just as midnight strikes. Suzu reveals the answer was Takeo's birthday, which is the day after her own. She congratulates Haru and chides Tokaku for her near-fatal mistake, calling her a "child." She then becomes the sixth assassin to be expelled.
After Black Class
In the final episode, she visits the grave of her dead loved one for the last time, saying she's going to stop looking at the past and accept her form of immortality.
In the doujin, it is revealed that Suzu almost walked off a bridge after her expulsion before running into Kouko, who had fled from Clover Home and was injured as a result. Suzu takes the other home and they begin to live together in quiet. She remarks that her body is on the verge of breaking due to her disease, implying there to be some sort of time limit on the amount of time she remains young before deteriorating. Before she dies, she hopes to leave behind proof she had lived. This prompts Kouko to say that she will outlive Suzu, making the other laugh.
Skills and Abilities
Suzu's intelligence gives her prior knowledge about the other members of the Black Class, such as Otoya Takechi's status as a serial killer or Sumireko Hanabusa's affiliation with a conglomerate. She claims she has no weapons of her own and she is not confident in her own strength. But her intellect and wit allow her to create elaborate traps, given the time and materials. For example, she commissioned the special bomb collar from Kouko after the latter had already been expelled.
Outside of assassination, Suzu is an excellent shogi player, having picked up the hobby from her days playing with Takeo. She is also a proficient swimmer and has learned over the years how to live out of the public eye, affording her and Kouko shelter after the events of Black Class.
- Her name Suzu (涼) means "refreshing" or "lonely". Her last name Shutō (首藤) means "first wisteria".
- Her birthday is on July 14th.
- The birthday of precious person she once had and her birthday is only one day apart from hers. Since she said that she'd age before he did every year, her birthday was earlier, therefore the birthday of that person was July 15th.
- When asked about her age, she claims to have forgotten. It was stated that Suzu was born around the Meiji Restoration era (1868 to 1912), therefore she is roughly over 100 years old. 
- She was born in July, the 7th month of the year, her attendance number was 7, and she was expelled out of the school on the 7th episode.
- After she is expelled, there is a red tulip placed on her desk, which symbolize "Declaration of Love".
- Her hobby is shogi (Japanese chess)
- Her favorite food is suama (a type of Japanese sweet) and her least favorite food is meat.
- She sleeps in average 10 hours.