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Human Specimens Season 1 poster
Complete Human Specimens

Human Specimens Season 1 Episode release dates & where to watch

Released

Friday, December 19, 2025

All episodes at once

When does Human Specimens Season 1 come out?

All 5 episodes of Human Specimens Season 1 were released at once on Friday, December 19, 2025 on Prime Video.

Last updated

Human Specimens Season 1 release schedule

Human Specimens Season 1 episode release dates
Episode Release date

1. Episode 1

The bodies of young boys were found in six cases. Shiro Sakaki, a professor considered Japan's leading expert on butterflies, turns himself in. He has recorded everything in a report published on the Internet, from his motive to the process of his creation. The interrogation proceeds as if tracing his distorted record, leading to a sensational suspense story where beauty and madness intertwine.

Friday · 10 months ago

2. Episode 2

Shiro starts to express his artistic viewpoint during interrogation. The art camp is canceled when Rumi falls ill. Shiro goes to the mountain to take the boys home. In the warehouse, there are six cases on display. Shiro feels emotional upheaval due to his expectations toward Itaru. As the detective investigates further, a big mystery arises, and the interrogation gets to the crux of his story.

Friday · 10 months ago

3. Episode 3

After creating five specimens, Shiro's final target is his beloved son, Itaru. Despite the memories with Itaru, Shiro only sees his son as a butterfly. Shiro makes up his mind to create his last specimen. At last, the report named "Human Specimen by Shiro Sakaki" seems to have ended. However, the letters in the report start to get distorted, and the story shifts to a new perspective.

Friday · 10 months ago

4. Episode 4

Itaru stays home while Shiro leaves for an observation survey of butterflies. Itaru stares at his father's specimens and invites his friends over. He starts recording his observations in his own report. When Shiro returns, they have dinner and share memories. Shiro opens his son's computer with a strange feeling about the specimens in his room.Three years later, Shiro receives a letter from Anna.

Friday · 10 months ago

5. Episode 5 Finale

Anna seemed proud, but she longed for a successor while looking at her mother, in the spotlight for her art book. After the art camp is canceled, Anna invites the boys to the mountain house. She insists she made the Human Specimen. Shiro understands Itaru's hopes to become his father's specimen. The truth of Itaru's death and the mystery of Anna's confession will be unraveled.

Friday · 10 months ago

Human Specimens Season 1 guest stars

  • Jun Murakami

    Jun Murakami

    Ichiro Sakaki

  • Aoba Kawai

    Aoba Kawai

    Kozue Sakaki

  • Miwako Ichikawa

    Miwako Ichikawa

    Sawako Ichinose

  • Hideaki Murata

    Hideaki Murata

    Kimihiko Ichinose

  • Yoshinari Furuya

    Yoshinari Furuya

    Police officer at the local station

  • Yua Shiraishi

    Yua Shiraishi

    Shiro Sakaki's student

  • Yurina Tsubaki

    Yurina Tsubaki

  • Eri Ota

    Eri Ota

  • Yura Kimura

    Yura Kimura

    Shiro Sakaki (young)

  • Renwa Sato

    Renwa Sato

    Rumi Ichinose (young)

  • Yasushi Fuchikami

    Yasushi Fuchikami

    Detective Narumi

  • Shunsuke Tanaka

    Shunsuke Tanaka

    Detective Katagiri

  • Tomorowo Taguchi

    Tomorowo Taguchi

    Man walking his dog

  • Mitsuyo Tsukada

    Mitsuyo Tsukada

    Toru Shirase's grandmother

  • Kaori Takeshita

    Kaori Takeshita

    Mieko (Dai Kuroiwa's fan)

  • Hina Michikita

    Hina Michikita

    High school student

Human Specimens Season 1 FAQ

When does Human Specimens Season 1 come out?

Human Specimens Season 1 premiered Friday, December 19, 2025 on Prime Video.

How many episodes are in Human Specimens Season 1?

Human Specimens Season 1 has 5 episodes.

Are new episodes of Human Specimens Season 1 released weekly?

All episodes are released at once.

When is the Human Specimens Season 1 finale?

The Human Specimens Season 1 finale (Episode 5) aired Friday, December 19, 2025.

How do I get notified when new Human Specimens Season 1 episodes are released?

Download the Streambay app and follow Human Specimens. You'll get a push notification the moment each new episode is out.

Never miss Human Specimens Season 1.

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