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World Trigger Wiki

This page is about the character. For other uses, see Osamu Mikumo (disambiguation).

...It's nothing so noble. I just think... If I ran away from what I think I should do even once, then surely, I'd end up running away when it matters most. I know the kind of person I am. I'm not doing it for others. I do it for myself.

Osamu Mikumo to Yūma Kuga.[1]Osamu tells Yūma his reason to help others.

Osamu Mikumo (()(くも) (おさむ) Mikumo Osamu?) is one of four main characters in the manga and anime series World Trigger. He is a modest high schooler who had originally joined Border in hopes of protecting his friend Chika, but quickly becomes the Captain and Shooter of Tamakoma Second.[8]


Osamu is a boy of average height with medium length black hair who wears glasses. For school, Osamu wears a blue suit top and gray bottoms traditional of Japanese high school students. When not in school or his Trion body, he usually wears a sweater and a striped scarf.

When in Trigger mode (C-rank) Osamu gains an all-white suit with Border emblem patches on the shoulders with a long yellow stripe going down the middle of each sleeve. When in his B-rank attire Osamu has on a blue jacket with a guard on the left shoulder. His left sleeve has a thick black stripe running through it, with a thinner, white stripe in the middle of the black one, and ending in the shoulder guard. On his shoulder guard, he has the Tamakoma Branch Symbol. His unit's emblem is located on his left chest.


Osamu going into battle to protect students

Osamu is a very honest person, as noted by Yūma Kuga who has the ability to discern lies and is thus very trusting of Osamu. Osamu is very determined and courageous, always going out of his way to help others even if he puts himself in harm's way. He has a strong sense of justice. It is implied by Jin that his reason for joining Border was to help others (in particular Chika). On the other hand, Tachikawa labeled him a ruthless individual, using crafty strategies to win battles.[9]

Osamu knows he has a limited talent for direct combat and that he is not nearly as proficient with his trigger as his teammates or other Border members. He recognizes his weakness and strives to become stronger.

Kazama's advice to fulfill his duties as a captain had an impact on Osamu since it allowed him to change his approach and make his team stronger rather than just focusing on himself. This change in thinking has allowed Osamu to think outside the box and strengthen his team by pursuing ambitious ideas such as asking Jin to join his team, agreeing to allow a formerly hostile neighbor to be part of his team and finally using negotiation tactics such as controlling the flow of the conversation by implanting "agents" in a room, a tactic he learned from Eizō Netsuki when it was used against him in the press conference.


Kasumi Mikumo[]

Not much of their relationship has been seen, but Kasumi initially disapproved of her son joining Border.[10] After noticing nobody who visited Osamu said he should leave Border, and after watching his speech, she seemingly changed her mind.[11] She also seems to believe Osamu and Chika's relationship is more than friendship, as she repeatedly tries pushing them together.[12]

Rinji Amatori[]

Rinji was Osamu's tutor and is Chika's older brother, whom Osamu looks up to. He promised to Rinji that he'd protect Chika. After he disappeared, Osamu became Chika's guardian and tried joining Border to better protect her.[citation needed]

Tamakoma Second[]

Yūma Kuga[]

Osamu acts as the voice of reason for Yūma and teaches him about Earth's customs. Despite originally conflicting due to their different beliefs and upbringings, they grew to trust each other and become great friends, with both willing to risk their lives to help each other.[citation needed]

Chika Amatori[]

Chika is the younger sister of Osamu's tutor, to whom he promised that he would protect her,[13] which is part of the reason why he joined Border. He was the only person whom she trusted after the disappearance of her friend and brother before she joined Border. He is always encouraging her, and she has much trust in him, too.[citation needed]

Tamakoma Branch[]

Yūichi Jin[]

Jin saved Osamu from a Neighbor, after the latter tried to break into Border's HQ, and helped him join Border as a combatant. Jin is also one of the people who see potential in Osamu, always encouraging him to do his best. As a result, Osamu looks up to him.[citation needed]

Kyōsuke Karasuma[]

Kyōsuke is Osamu's teacher at Tamakoma, and thus is always encouraging him to fight with his full power. He considers Osamu weak but intelligent, encouraging him to become stronger and to fight offensively rather than defensively.[citation needed] He even went to such lengths at Osamu's request as to equip Ninomiya's trion levels as a shooter in virtual combat zone in preparation for Tamamkoma Second's upcoming match, should they have to fight-on-one with the #1 Shooter.

Shiori Usami[]

Usami is the operator for Osamu's team.

Yōtarō Rindō[]

At first, Yōtarō thought that Osamu was weak, but he grew fond of Osamu even becoming enraged at how Border wanted to use him as a scapegoat.

Reiji Kizaki[]

Kirie Konami[]

Arashiyama Unit[]

Jun Arashiyama[]

Arashiyama became friends with Osamu after he and Yūma saved their school along with its students, including his siblings Saho and Fuku. He praised Osamu for his good work, rather than scolding him, despite Osamu breaking the rules of Border. He is always eager to help him.[14]

Ai Kitora[]

Osamu has a lot of respect for Kitora, who originally chided him for breaking Border's rules, but later saw how good he really is. She is always trying to outsmart him, but he doesn't really care. She seems to be interested in his growth. She also envies him for being Karasuma's student.[citation needed] He later asks her to train him to better fight with his low trion level.[15] Despite her harshness and criticism towards Osamu,[16] she does believe in Tamakoma 2's potential as later acknowledged that if Tamakoma 2 was utilized properly they could easily score more points in rank wars.[17] She is also the one to suggest and train Osamu to incorporate the Spider trigger into his fighting style, for which Osamu himself seems very grateful.[18]

Mitsuru Tokieda[]

Shun Midorikawa[]

Midorikawa initially felt envious of Osamu's newfound fame because of the rumor about his tie with Kazama, on top of being in Tamakoma with Jin.[citation needed] However, when Yūma beat him, he started to show respect towards Osamu, calling him "senpai."[citation needed] During the A-Rank evaluation of the Away Mission Test temporary units, he doubted his captain's remarks regarding Mikumo's slower pace, thinking smugly, "I dunno, Saki... You didn't see the matches that Mikumo won with his wires," implying he's since kept tabs on the up-and-coming combatant.[19]

Tachikawa Unit[]

Kōhei Izumi[]

Mikumo once asked Izumi to teach him composite bullets; instead, he offered Osamu the chance to train with his teammate Yuiga. Upon arrival, Izumi promptly apologizes to his guest following a merciless dropkick to his squad member for harrassing Osamu.[20]

Takeru Yuiga[]

Yuiga is an A-ranker by sponsorship that has a personality that is the opposite of Osamu's. However, they get better than most, with Yuiga offering Osamu as many 1.v.1 matches as he'd like;[21] though this may be due to Osamu's reserved nature, so as to not upset his opponent further.[citation needed]

Shirō Kikuchihara[]

Following the Top Brass meeting regarding Hyuse, Kikuchihara is quick to confront Osamu about his meager contributions to the team made especially stark the day before, to which Osamu replies grimly, 'Yes... I think so too.'[22]


  • (To Yūma) "Even though my chances of winning are slim, I still can't run away." [23]
  • (To Yūma) "It's nothing so noble. I just think... If I ran away from what I think I should do even once, then surely, I'd end up running away when it matters most. I know the kind of person I am. I'm not doing it for others. I do it for myself." [24]
  • "Forks in the road don't wait for us to choose. If I wait until all my ducks are in a row, I might never get anything done in my lifetime."[25]
  • "I'm not a hero. I can't make anyone happy with any result. I can only do what I deem right with me not hating my choice at a later point."[26]
  • "I'll get them back. Your family members that were taken by the neighbors... your friends... we'll get them back. You don't have to tell me about taking responsibility. It's the obvious thing to do."[27]


  • "Osamu," written with the kanji "修," means "discipline," which fits Osamu's personality. "Mikumo" (三雲?) literally means "three clouds."
  • Osamu seems to be left-handed since he carries his sword in his left hand which is holstered on his right side. He also uses chopsticks with his left hand. During his coma-flashback in the hospital, he appears to fill out a bubble-in aptitude exam for Border using his left hand.[28]
  • He likes his parents' homemade cooking and bridges.
    • According to Ashihara's Q&A, he likes his mother's handmade cream croquettes with her special white sauce the best.
  • He came 1st in the First Character Popularity Poll.
  • Osamu made a cameo on a special chapter of Saiki Kusuo no Ψ Nan.
  • Ōji's nickname for Osamu, "Ossam," might be a pun on "Ossan" (おっさん?), which is short for "Ojīsan" (おじいさん?), meaning "old man."
  • It is possible Osamu equipped Spider to the Sub instead of Main during the match against Katori and Kakizaki Unit. In fact, he is seen using it in conjunction with Raygust, which is equipped to the Main, eight times,[18][29][30][31][32][33][34][35] and almost always with his non-dominant hand. However, he seems to have changed its placement again before his follow-up match.[36]
    • During that rank battle, however, he again uses it at the same time as Raygust on one occasion, which should be impossible.[37]
  • Osamu is prone to feeling a heavy, anxiety-ridden sensation in his chest.[38][39]


  1. World Trigger Manga and Anime — Vol. 1 Chapter 21 (p. 12) and Episode 11.
  2. World Trigger Manga and Anime — Vol. 1 Chapter 1 (p. 49) and Episode 1, Osamu introduces himself to Yūma.
  3. World Trigger Manga and Anime — Vol. 1 Chapter 1 (p. 1, 49) and Episode 1, Jin (pages 1 and 49) and Yūma (page 49) call Osamu by the nickname.
  4. World Trigger Manga — Vol. 17 Chapter 151 (p. 1).
  5. World Trigger Manga Chapter 196 (p. 22)
  6. World Trigger Manga and Anime — Vol. 11 Chapter 94 (p. 14) and Episode 43.
  7. World Trigger Manga and Anime — Vol. 13 Chapter 112 (p. 1) and Episode 68.
  8. Daisuke Ashihara: For me, all four of the characters drawn on chapter 1's title page are the protagonists.
    Source: Question Corner 7, Volume 8
  9. World Trigger Manga and Anime — Vol. 12 Chapter 102 (p. 20) and Episode 47.
  10. World Trigger Manga and Anime — Vol. 10 Chapter 85 (p. 15) and Episode 38.
  11. World Trigger Manga and Anime — Vol. 10 Chapter 85 (p. 16) and Episode 38.
  12. World Trigger Manga Chapter 83 (p. 2)World Trigger Manga Volume 10 (p. 2)
  13. World Trigger Manga Chapter 82 (p. 11)
  14. World Trigger Manga — Vol. 13 Chapter 107 (p. 12).
  15. World Trigger Manga and Anime — Vol. 14 Chapter 122 (p. 8) and Episode 73.
  16. World Trigger Manga Chapter 109 (p. 17)
  17. World Trigger Manga Chapter 146 (p. 5)
  18. 18.0 18.1 World Trigger Manga Chapter 140 (p. 18)
  19. World Trigger Manga Chapter 206 (p. 20)
  20. World Trigger Manga Chapter 109 (p. 12)
  21. World Trigger Manga Chapter 110 (p. 3)
  22. World Trigger Manga Chapter 104 (p. 16)
  23. World Trigger Manga and Anime — Vol. 1 Chapter 4 (p. 4) and Episode 2, Yūma tells Osamu to leave the Mole Mods for Border's stronger agents.
  24. World Trigger Manga and Anime — Vol. 1 Chapter 21 and Episode 11, Osamu tells Yūma his reason to help others.
  25. World Trigger Manga Chapter 85 (p. 6)
  26. World Trigger Manga Chapter 85 (p. 7)
  27. World Trigger Manga Chapter 85 (p. 8-9)World Trigger Manga Volume 10 (p. 8-9)
  28. World Trigger Manga Chapter 82 (p. 12)
  29. World Trigger Manga Chapter 141 (p. 1)
  30. World Trigger Manga Chapter 141 (p. 14)
  31. World Trigger Manga Chapter 141 (p. 18)
  32. World Trigger Manga Chapter 143 (p. 10)
  33. World Trigger Manga Chapter 143 (p. 11)
  34. World Trigger Manga Chapter 145 (p. 13)
  35. World Trigger Manga Chapter 145 (p. 15)
  36. World Trigger Manga Chapter 152 (p. 12)
  37. World Trigger Manga Chapter 156 (p. 6)
  38. World Trigger Manga Chapter 84 (p. 12)
  39. World Trigger Manga Chapter 164 (p. 18)


Trigger: Yūma's Trigger  •  Raygust  •  Scorpion  •  Egret  •  Ibis  •  Lightning  •  Bagworm  •  Grasshopper  •  Shield  •  Spider  •  Lead Bullet
Side Effect: Lie Detector, Neighbor Detection, Trion Hiding

Triggers: Kogetsu  •  Scorpion  •  Raygust  •  Thruster  •  Meteor  •  Asteroid  •  Hound  •  Viper  •  Spider  •  Lead Bullet  •  Egret  •  Ibis  •  Lightning  •  Grasshopper  •  Bagworm  •  Shield  •  Escudo
Exclusive Trigger: Sōgetsu  •  Connector  •  Geist  •  Full Arms
Black Trigger: Ring
Side Effects: Clairvoyance  •  Lie Detector  •  Neighbor Detection  •  Trion Hiding
e d vBorder
Commander in Chief Masamune Kido
Administration Eizō NetsukiKatsumi KarasawaKyōko SawamuraMasafumi ShinodaMotokichi KinutaTakumi Rindō
General Staff Mikhael CroninRaizō TerashimaSeiji Mizunuma
S-Rank Tsukihiko Amō
A-Rank Ai KitoraAsumi AmakuraFutaba KuroeHayato UnoIsami TōmaJun ArashiyamaKazuma SatomiKei TachikawaKen SatoriKirie KonamiKōhei IzumiKyōsuke KarasumaMai KitagawaMitsuru TokiedaNozomi KakoReiji KizakiRyō UtagawaRyūji SaekiShinji FuyushimaShirō KikuchiharaShōhei KoderaShūji MiwaShun MidorikawaSōya KazamaTakaaki KatagiriTakeru YuigaTōichirō MomozonoTōru NarasakaYōsuke YoneyaYūichi JinYukimaru Ichijō
B-Rank Atsushi HokariChika AmatoriDaichi TsutsumiFumika TeruyaHanao TsukimiHaruaki AzumaHidetaka KitazoeHiro KitazoeHisato Sasamori • Hitoshi Matsushiro • HyuseItsuki FujisawaKai MinamisawaKazuaki ŌjiKazuki KurauchiKazuto TonookaKeizō MamiyaKō MurakamiKōji OkiKōtarō SuwaKotarō TomoeKuniharu KakizakiMakoto Chano • Mamoru Tokiwa • Masakuni Hakoda • Masataka NinomiyaMasato KageuraMinoru HataMitsuya KoinumaNoboru KoaraiOsamu MikumoRei NasuRokurō Wakamura • Ryōgo Funabashi • Satoru Hayakawa • Satoshi Mizukami • Seiji Marui • Shinnosuke Tsuji • Shō Motegi • Sumiharu InukaiTaichi Betsuyaku • Takahiro Ebina • Takuma YubaTatsuhito IkomaTatsuya KurumaTetsuji Arafune • Tokiya Saitō • Tsuneyuki Okudera • Waka Utsunomiya • Wataru UrushimaYōko Katori • Yoshinobu Kera • Yoshito HanzakiYūichirō YoshizatoYukari Obishima • Yukito Otokawa • Yūko KumagaiYūma KugaYūta MiuraYutaka Kashio • Yūya Tsuchisaki • Yuzuru Ema
C-Rank Fumifumi SaotomeHidehide HinoeIzuho NatsumeTeruteru Kōda
Operators Aki HiyamiAn KobayakawaAoi Kusumoto • Asami Taya • Asuka Asagiri • Ayumu Hatori • Hana SomeiHaruka AyatsujiHaya Kittaka • Hazuki Nanao • Hikari NireKaho MikamiKarin YuitsukaMadoka UiMako HitomiMaori HosoiMegumi TokuraNono FujimaruRen TsukimiRika RokutaRin KagamiRisa MakiRui OsanoSaki KusakabeSakurako TaketomiSayoko ShikiShiori UsamiYuka KonYuri RindōYuu Kunichika
Former Border Agents Akane HiuraMirai HatoharaShin KazamaSōichi MogamiTadaomi KandaYūgo Kuga
Affiliated Personel RaijinmaruReplicaRinji AmatoriRuka ShinodaYōtarō Rindō
Squads Arafune SquadArashiyama SquadAzuma SquadChano SquadEbina SquadFuyushima SquadHayakawa SquadIkoma SquadKageura SquadKakizaki SquadKako SquadKatagiri SquadKatori SquadKazama SquadKizaki SquadKuruma SquadKusakabe SquadKōda SquadMamiya SquadMatsushiro SquadMikumo SquadMiwa SquadNasu SquadNinomiya SquadŌji SquadSuwa SquadTachikawa SquadTokiwa SquadUrushima SquadYoshizato SquadYuba Squad
Branches Hayanuma Branch • Hisama Branch • Suzunari BranchTamakoma Branch • Wataayu Branch • Yumite District Branch
Factions Kido FactionShinoda FactionTamakoma Branch
Triggers AsteroidBagworm • Bagworm Tag • Bail OutChameleon • Cobra • ConnectorDummy BeaconEgret • Enhanced Radar • EscudoFūjinFull ArmsFull AttackGeistGimletGrasshopperHornetHoundIbisIdatenKogetsu (Spear/Gen'yō/Senkū) • Lead BulletLightning • Makō • MeteorRadarRaygust (Shield Mode/Thruster) • RingSalamanderScorpionShield (Fixed Mode/Full Guard) • Silencer • Sōgetsu (Axe) • SpiderStarmakerSwitchboxTeleporter • Timer • TomahawkTrion BodyViper