Prime Video is set to deliver a powerful new Japanese mystery series titled Human Specimens this December. The show is based on a novel by celebrated author Kanae Minato and features a standout cast led by acclaimed actor Hidetoshi Nishijima. All five episodes of this chilling story will be available to stream at once, making for a perfect weekend watch for thriller fans around the world.
The series follows a university professor, Shiro Sakaki, who confesses to a shocking crime: he says he has turned six young boys, including his own son, into “human specimens.” As the story unfolds through multiple viewpoints, it explores deep themes of family, obsession, and the complex line between art and madness. This guide introduces the talented actors who bring this dark and compelling story to life.
The Main Cast and Their Key Roles
The core of Human Specimens revolves around a small group of characters whose fates are tightly connected. The drama builds around their relationships and the secrets they keep.
- Hidetoshi Nishijima as Professor Shiro Sakaki: Nishijima takes on the lead role of a respected butterfly researcher. His character stuns everyone by admitting to the horrific crimes. Known internationally for his Oscar-winning role in Drive My Car, Nishijima is no stranger to complex characters. He described the project as a major challenge, stating he wanted to participate as soon as he heard about it.
- Somegoro Ichikawa as Itaru Sakaki: Playing the professor’s son is rising star Somegoro Ichikawa. This role marks his first appearance in a modern television drama, a significant step from his famous work in traditional Kabuki theater. Director Ryuichi Hiroki cast him to portray the son caught in this tragic situation.
- Rie Miyazawa as Rumi Ichinose: Miyazawa plays a world-famous artist and a childhood friend of Professor Sakaki. Her character, known as a “magician of color,” organizes the art workshop that brings the key characters together. She is a pivotal figure in the story’s mysterious events.
- Aoi Ito as Anna Ichinose: Ito portrays the daughter of Rumi Ichinose. While details about her role are limited, official sources confirm she is part of the central cast, suggesting she holds clues to the unfolding mystery.
Meet the Talented Young Artists at the Story’s Heart
The story involves six promising young artists who attend a workshop at a remote mountain villa. Each actor brings a unique character to the screen.
- Towa Araki as Toru Shirase: An artist who creates a unique world using only black and white in his ink paintings.
- Jyutaro Yamanaka as Hikaru Akabane: A quiet young man who expresses a hidden passion through vivid paintings of red roses.
- Kodai Kurosaki as Sho Ishioka: A talented wall art painter who has overcome a difficult personal history.
- Reo Matsumoto as Ao Fukazawa: An elite student from a top art school who specializes in creating unique blue-themed artworks.
- Ikuho Akiya as Dai Kuroiwa: A new artist gaining attention under the name “BW,” known for satirical drawings that critique society.
The Creative Team Behind the Scenes
A story this complex requires an expert creative team. Human Specimens is in the hands of some of Japan’s most respected storytellers.
The series is directed by Ryuichi Hiroki, a filmmaker known for his nuanced portrayals of human psychology in award-winning movies like April Bride and The Waxing and Waning of the Moon. This is his second collaboration with author Kanae Minato, following the 2022 film Motherhood. Hiroki said he was captivated by the novel’s sharp insight into human nature and its beautiful, butterfly-inspired world.
The source material comes from bestselling author Kanae Minato, famous for intense psychological mysteries like Confessions. For this novel, she tackled a difficult theme she had been considering for a decade. She has expressed strong confidence in the filmed version, stating, “I strongly wished for it to be adapted, and my wish has been granted in the best possible form”.
Release Date and Global Streaming Details
Mark your calendars: Human Specimens will be released globally on Prime Video on December 18, 2025. Some regions, including Japan, may see the release listed as December 19 due to time zone differences.
All five episodes of the series will be released at the same time, a method known as a “full season drop”. This means viewers can watch the entire story at their own pace as soon as it becomes available. You will need an active Amazon Prime or Prime Video subscription to stream the show.
“The fact that ‘humans have been turned into specimens’ creates a completely different view depending on the perspective, and in the end a truth that no one could have imagined emerges. I found this intriguing,” said lead actor Hidetoshi Nishijima about what drew him to the role.
For fans of intricate, psychological mysteries, Human Specimens promises to be a memorable and thought-provoking addition to Prime Video’s international lineup.
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