Darker than Black Wiki
Darker than Black Wiki
Ōtsuka Mayu
S1E18 Mayu
Real Name Mayu Ōtsuka
Alias MayuMayu
Gender Female
Race Human
Professional Status
Affiliation Section 4
Occupation National Observatory Liaison
Team Misaki Kirihara, Yutaka Kōno, Yūsuke Saitō
Former Team Kunio Matsumoto
Behind The Scenes
First Seen Season 1, Episode 1
Japanese Voice Yūna Inamura
English Voice Leah Clark

Mayu Ōtsuka (大塚 真由 Ōtsuka Mayu) is Section 4's liaison officer with the National Astronomical Observatory of Japan.


Ōtsuka has brown hair and brown eyes.[1]


In her private time, Ōtsuka is an otaku who enjoys anime and does anime/manga-based fanfiction stories. She was in the manga club at university and has numerous anime posters, figurines in her and trophies in her room. She is currently in to the “Rose of Maurice” anime. She writes stories for a hobby under the pen name "MayuMayu" and has many doujin and claims to have many fans. She has hayfever. She is adept at winding people up, such as suggesting to Matsumoto that she is interested in older men like him.[2]

Part in the Story[]

The Black Contractor[]

S1E4 Otsuka, Misaki and Kanami

Ōtsuka with Kanami and Misaki in the Observatory.

Ōtsuka works as the liaison between the Public Security Bureau and National Astronomical Observatory. During the investigation in to the death of the Contractor Louis, she attends a briefing with Yoshimitsu Horai and Misaki Kirihara's team. She reports that the Contractor BK-201 was active at the time of Louis' death and that this is a Contractor on which they have no information.[1] Later, Ōtsuka and Kanami Ishizaki greet Misaki upon arrival at the Observatory. While Kanami briefs Misaki on the activity of Mai Kashiwagi, Ōtsuka informs her that they have evacuated the area surrounding Mai's believed location under the pretence of a broken gas pipe. She later informs Misaki of Mai's exact location.[3]

When Misaki and Saito are searching near Hell's Gate for the Regressor Havoc, Ōtsuka rings them to let them know that the Observatory believes that Havoc may be regaining her powers. Misaki tells her to organise a security team.[4]

S1E15 Otsuka Mayu and Kanami Ishizaki

Ōtsuka and Kanami Ishizaki talk over lunch at the Observatory.

During the build up to the Solar Maximum approximately five years after the disappearance of Heaven's Gate, Kanami tells her about the event and how it is one of the indicators of a Gate disappearing. When she asks what other indicators there are, she is interrupted by Hoshimi beginning to speak, another indicator, and the pair rush to hear what she has to say.[5]

Sometime later, Ōtsuka reports to Misaki Kirihara that BK-201 was active in Shinjuku for several minutes, linking the activity with the murder of Hitotsubashi.[6]

During the battle between Evening Primrose and PANDORA, Ōtsuka phones Yūsuke Saitō, complaining that nobody is answering the phone in the police headquarters. As people frantically run about the observatory, she tells him that she is scared and that the Solar Maximum will reach its peak soon.[7]

Shikkoku no Hana[]

[8] [9] [10] [11] [12] [13]


Season One Appearances
The Star of a Contract Fell... The New Star Twinkles... The Red Dream of a Calamity The Gardenia Gives Off Fragrance... The Pure White Dress Is Stained... Within the Wall...
On a Silver Night... The Memory of Betrayal I'll Sing a Love Song... Without Dreaming Shallow Dreams... The City of Regulations... God's in His Heaven...
Meteor Shower Is the Dream That a God of Death Has... Beneath Cherry Blossoms...


  • The name Mayu means "real, genuine" (真) (ma) and "reason, case, cause" (由) (yu).
  • Mayu's surname Ōtsuka means "big, great" (大) (ō) and "mound" (塚) (tsuka).


  1. 1.0 1.1 The Black Contractor, Episode 1
  2. The Black Contractor, Episode 26 (OVA)
  3. The Black Contractor, Episode 4
  4. The Black Contractor, Episode 6
  5. The Black Contractor, Episode 15
  6. The Black Contractor, Episode 18
  7. The Black Contractor, Episode 25
  8. Shikkoku No Hana; Chapter 4 pages 4-14 & 18-24
  9. Shikkoku No Hana; Chapter 5 pages 11-24
  10. Shikkoku No Hana; Chapter 8 pages 21-23
  11. Shikkoku No Hana; Chapter 10 pages 4-12
  12. Shikkoku No Hana; Chapter 14 page 5
  13. Shikkoku No Hana; Chapter 15 pages 5-6


v · e Public Security Bureau
Active members: Yūsuke SaitōNaoya KiriharaYutaka KōnoŌtsuka MayuIssei YanagiTatsuo Yabuta
Former members: Yoshimitsu HoraiHuangIsozakiMisaki KiriharaGai KurusawaKunio Matsumoto
v · e National Astronomical Observatory of Japan
Members: HoshimiKanami IshizakiŌtsuka Mayu
Related Articles: ContractorsDollsHell's GateNational Astronomical Observatory of JapanPublic Security BureauSaturn Ring