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Sachi Mizuiyama
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The article below is based on non-localized content only available in Japanese.
As such, all information in this article is based on fan-contributed translations.

Sachi Mizuiyama (水井 山 幸) is a character featured in Danganronpa Kirigiri, debuting in the third volume and became a reccurring character in the following novels.

Sachi is a 7th-rank detective specializing in technological crime and also specializes in architecture, as the first two digits of her number speak of - DSC 527.

She was one of the few detectives summoned to take part in the Duel Noir at the Takeda Haunted Mansion and the other Duel Noirs from the Twelve Zodiac Duel Noir Challenge taking on the Museum of Medieval Torture Devices Duel Noir.


Translation Credit: DJ Shocker, Jinjojess and @Edogawa Translations on Tumblr
Main article: Danganronpa Kirigiri

Prior Life

Prior to becoming a detective, Sachi was originally a school counselor at St. Anne's Academy thanks to her ability to read people. During that time, she got into an altercation with one of the students Hana Takezaki, and eventually left. Later, she registered into the Detective Library as a detective. However, during this time the Victims Catharsis Committee approached her and took up a Duel Noir against her old student as the culprit of the Libra Girls Academy case.

Takeda Haunted Mansion Duel Noir

Before the set-up of her case, she is called to the Takeda Haunted Mansion Duel Noir, on January 10th, alongside fellow detectives Hajiki Yaki, Salvador Fukuro Yadorigi, Kakitsubata Kanisu, and Suntasu Shirasu, with her letter asking her to check the architecture of the building. When the proxy no-shows, four of the five (except for Suntatsu) confess their true professions and decide to wait it out while there. During that time, Suntatsu is murdered by Kakitsubata in a locked room manner, though initially, it takes the arrival of Kyoko Kirigiri and Yui Samidare to discover that fact. During the investigation, Sachi is initially fingered as the culprit behind this Duel Noir and is arrested, but in reality, this was merely Kyoko's way of deceiving the true culprit, Kakitsubata, into revealing herself. However, Sachi would only learn of this later on and would still hold a grudge against Kyoko leading into the next day.


The next day, she is called out by Kyoko to the train station under the assumption that since she, alongside Hajiki and Salvador, was the third parties in the last Duel Noir she had no connection to the Committee and could be trusted. Sachi was wary of this and hid nearby until Hajiki and Salvador revealed themselves. Taking a ride in Salvador's car, she let it known she still held animosity towards Kyoko for having her falsely arrested until it was pointed out that she would have been framed for real if Kakitsubata's plan worked. As such, she backs down and calms down further whilst talking with Salvador, the two clearly taking a liking to each other. During the ride, she listens in on Yui's and Kyoko's request for assistance and initially doesn't want part of it. However, after both Hajiki and Salvador agree (with Salvador doing so to avenge his partner), she gives in to the pressure and joins, though claims its to help boost her reputation after being falsely arrested. With the team formed, she requests that they pick a Japanese sounding name, before Kyoko pushes the group to choose a Duel Noir. For this, she chooses to challenge the Museum of Medieval Torture Devices Duel Noir.

The Twelve Zodiac Duel Noir Challenge

Arriving at the museum, she is surprised by the place being open since it was previously closed as a result of its creepy atmosphere that unnerved nearby home owners. In the past, she asked to review such a location for it to be refurbished before it was decided to shut it down. Arriving on the scene, she uses her skills at lying to gain information on the case, such as learning that the victim Fukuju Idogaki (who worked for the nearby university) was dead and there was a fire of some sorts that charred the victim's body (even though the murder weapon as listed as an iron maiden). Needing more information, she tracks down one of the students of Idogaki by the name of Kadama Shindo. From him, she leads Idogaki was rumored to be a plagiarist who copied his own student reports and even murdered a researcher of his when she was going to expose him. She is then directed to meeting Kariyasu Karasuba at a nearby cafe, however, before that can happen, she runs into Licorne who warns her not to go overboard before disappearing. Sachi moves past the encounter and talks with Karasuba. There she learns that Karasuba used to be lovers with a girl named Shoko who was the researcher killed by Idogaki, and over the course of talking with him it becomes clear he is the culprit with his birthday being August 30th, thus making a Virgo and the culprit of this case. However, she doesn't stop there and goes back to the museum to figure out the trick to the case.

Later, Sachi meets with Hajiki, coming by to check in on the bar. When Hajiki explains the situation, she then explains that he had completely missed the culprit and breaks down the reasoning that it has to be Arai. When Hajiki realizes this, he thanks Sachi and invites her to come stop them. She agrees, but as soon as his back is turned, she bludgeons him in the head with a pipe. He survives the initial blow, but she kills him with another blow to the head. With Hajiki dead, she moves forward to her own Duel Noir at the Libra Girls Academy.

Her Duel Noir involved the kidnapping of two other students, Nazuna Tooakitsu and Tsukiyo Nada, as well as killing Hana as well. When Yui arrives, she disguises herself in a black robe and briefly knocks her out, waiting long enough for her to awaken before leaving in order to lead her into her trick to trap her. Her Duel Noir operated by use of modified rooms acting as scales, however, eventually, Yui was able to figure it out and the arrival of Salvador freed Yui's group. Sachi retaliated by bludgeoning Salvador with her pipe before trying to hold Yui up with a nail gun. She explains she used to work at St. Anne's and took up the Duel Noir against her old pupil. She also reveals her devotion towards Ryuzoji pushed her to go against Yui, with her not wanting him to step down as a head of the Victims Catharsis Committee and reveals that even if she lost her Duel Noir, she still could have tampered with the bar and museum cases to make them unsolvable. She intended to hold Yui at the academy to make the time limit for the challenge run out, but the interference of the Mystery Research Club that Salvador brought with him ruins such plans. She tries to kill them, but they manage to knock her out and it leads to her being arrested.


Sachi is a young woman with yellow-orange eyes, has long dark purple hair, and has very pale skin.

She wears a kimono and also wears glasses. According to Yui, she is miniature and because of this height, she can be mistaken for a child, but with the face of a beautiful intellectual.


Initially, Sachi comes across as intelligent and elegant, serving as one of the more sensible of the detectives during the haunted mansion case. Sachi has major pride in her Japanese heritage to the point of wearing a kimono during her work and when joining forces with Yui, she suggests they pick a Japanese name. However, she isn't above holding a grudge for slights since she keeps one against Kyoko after she had her falsely accused and briefly arrested of being the Duel Noir's culprit (though it was a trick to lure out the real one), and only drops it after it's pointed out she would have been arrested for real. This unwillingness to let go of a grudge may have potentially led her to take up the Duel Noir to kill a student of hers back when she worked as a school counselor.

She's also a fairly cautious individual, such as when she observes who would show up when called out to meet after the mansion Duel Noir, and doesn't usually want to take risks with her life at stake, like when she initially refuses to take part in the effort to the Duel Noir. Because of this cautiousness, she is even willing to lie if she doesn't feel it is safe and is fairly skilled in it. Despite this, she does cave when peer pressure is on her and does agree to it in the end, though claims it's to help her pride. She is also quite skilled at reading people and the environment to the point she even has experience as a school counselor. However, she prefers to inspect buildings instead, finding them far more interesting.

She was someone incredibly devoted to Ryuzoji and didn't want him to be defeated by Yui, to the point she was willing to kill, hurt and sabotage people in order to do it. It's implied she was also doing this as a result of being jealous and bitter of Yui being chosen to challenge him. She also confesses to lacking the conviction of upholding justice compared to Ryuzoji.


v  e
Danganronpa Zero Ryoko OtonashiYasuke MatsudaChihiro FujisakiIsshiki MadaraiIzuru KamukuraJin KirigiriJunko EnoshimaKyoko KirigiriMakoto NaegiMukuro IkusabaThe Steering CommitteeSōshun MurasameThe Student CouncilYuto Kamishiro
Danganronpa Kirigiri Kyoko KirigiriYui SamidareDetective Library membersFuhito KirigiriGekka RyuzōjiHajiki YakiJin KirigiriLicorneMikado Shinsen • Nazuna Tooakitsu • Norman's Hotel Murder Case participantsSachi MizuiyamaSae YozuruSalvador Fukuro YadorigiSuisei NanamuraTadashi AsakuraTōkichirō Endō • Tsukiyo Nada
Kirigiriso Kyoko Kirigiri • Kouhei Matsudaira • Santa ShikibaKyouka
Danganronpa: Togami Byakuya Togami • Blue InkAloysius PennyworthSuisei NanamuraTaeko KanaiUltimate Imposter
Short Stories Danganronpa:
Trigger Happy Havoc IF
Mukuro IkusabaJunko EnoshimaAoi AsahinaByakuya TogamiCelestia LudenbergChihiro FujisakiGenocide JackHifumi YamadaKiyotaka IshimaruKyoko KirigiriLeon KuwataMakoto NaegiMondo OwadaMonokumaSakura OgamiSayaka MaizonoToko FukawaYasuhiro Hagakure
Makoto Naegi Secret File Makoto NaegiKomaru NaegiJin Kirigiri
Ultra Despair Hagakure Yasuhiro HagakureKanon NakajimaKotoko UtsugiMasaru DaimonLeon Kuwata
Danganronpa 1 ・2 Beautiful Days
MonokumaMonomiAkane OwariAoi AsahinaByakuya TogamiCelestia LudenbergChiaki NanamiChihiro FujisakiFuyuhiko KuzuryūGundam TanakaHajime HinataHifumi YamadaHiyoko SaionjiIbuki MiodaKazuichi SōdaKiyotaka IshimaruKyōko KirigiriLeon KuwataMahiru KoizumiMakoto NaegiMikan TsumikiMondo ŌwadaMukuro IkusabaNagito KomaedaNekomaru NidaiPeko PekoyamaSakura ŌgamiSayaka MaizonoSonia NevermindTeruteru HanamuraTōko FukawaYasuhiro Hagakure
For minor characters, see: Minor Characters