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Sirex

UNDER NINJA

Within the shadows of Japan, a covert battle wages on. Around 200,000 ninjas still exist carrying out deadly missions as a secret organization, National Intelligence of NINJA, or NIN. But a challenger arises: UNDER NINJA. Known as UN, these ninjas oppose NIN at every turn. One such UN is Kuro, a high school loner sent to the front lines. What will be his fate and which faction will prevail?

IMDb 6.512 episodes2025HDU/A 18+ [A]

Action•Anime•Military and War•Animation•Adult Interest

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Japanese

Episode Related Details

S1 E1 - Throw a Rock, Hit a Ninja

May 10, 2025 • 24m•U/A 18+ [A]

Kumogakure Kuro is a modern day ninja, but that doesn't mean his life is exciting. Bereft of any missions for a long time, he's an underachiever whiling away his days in obscurity, until he receives a special delivery.

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S1 E2 - I Want to Be a Ninja

October 13, 2023 • 24m•U/A 18+ [A]

Kuro's been assigned a mission to infiltrate Kodan High School, but while waiting for his enrollment to finish, he's tasked with confronting a mysterious assailant with a very particular target.

Included with Prime

S1 E3 - Boobs: So Close, Yet So Far

October 20, 2023 • 24m•U/A 18+ [A]

Kuro sets a trap and catches a high school boy named Eita. Upon returning home Eita encounters Junna who wants to borrow his drone. Eita agrees to let her if she can find the blond foreigner.

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S1 E4 - Do You Know What the Ninja Code Says?

October 27, 2023 • 24m•U/A 18+ [A]

The confrontation between the Foreigner, Suzuki and Hibi continues. Junna's stepfather arrives at the location of the conflict and begins to yell at her for being outside. Then the Foreigner attacks him.

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S1 E5 - Kumogakure Is Within the Top 10 Common Family Names in Japan (Lying)

November 3, 2023 • 24m•U/A 18+ [A]

Kuro goes to take his placement tests for school where he meets Noguchi who is there for extra lessons. After the tests Kuro and Noguchi walk home together and Kuro introduces her to Kawado.

Included with Prime

S1 E6 - The Lid on This Hellish Cauldron Has Come Off

November 10, 2023 • 24m•U/A 18+ [A]

After coming to Eita's aid in a conflict with some school delinquents, Kuro makes his way to the school's boiler room where he confronts the director. Later on the defeated Noheji requests Kuro's aid in fighting some students from Yankii High.

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S1 E7 - Meow Meow, Meow Meow, Meow Meow Meow Meow Meow?

November 17, 2023 • 24m•U/A 18+ [A]

After the lady at the convenience store is attacked by an invisible individual and killed, an Emergency Shinobi Notice is sent out and an investigation is launched in an effort to ascertain the identity of the culprit.

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S1 E8 - Every Last Ninja on the Surface Will Be Annihilated

November 24, 2023 • 24m•U/A 18+ [A]

Kuro scares Noguchi after sneaking into her room to tell her not to go to school. Yoshida recounts his history of being a writer and how it was influenced by various ninja.

Included with Prime

S1 E9 - I'm Gonna Go Down in Shinobi History

December 1, 2023 • 24m•U/A 18+ [A]

Ranran finishes her analysis of the UN's invisibility suit and sends her findings to Kato. Saruta begins his attack on the school and starts cutting down the students and faculty.

Included with Prime

S1 E10 - DAYS GONE BY AND DAYS TO COME

December 8, 2023 • 24m•U/A 18+ [A]

The battle at the school continues on. Kato engages the RWS to keep anyone from leaving school grounds and then he deploys the Cube, a war machine, to aid in taking down Saruta.

Included with Prime

S1 E11 - Kuro Finally Took Up a Sword

December 15, 2023 • 24m•U/A 18+ [A]

Hibi loses his fight to Yamada and now it's time for Kuro to step up to the plate. Noguchi encounters Sato and Suzuki while following orders from the Director and he leads them into a secret underground facility formerly run by the Japanese army.

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S1 E12 - Business as Usual, Wrapped Up Tidy

December 22, 2023 • 23m•U/A 18+ [A]

The battles at the schools reach their climax. When all is said and done who will be left standing and what will be the outcome?

Included with Prime