Kei Yuuki

Original Name 結城 蛍
Romaji Name Yuuki Kei
Nicknames N/A
Series Moyashimon
Age N/A
Weight N/A
Height N/A
Date of Birth N/A
Blood Type N/A

Kei Yuuki from “Moyashimon”: A Character Analysis

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Kei Yuuki, a character from the anime series “Moyashimon”, has a complex and multifaceted personality. Initially introduced as a childhood friend of the protagonist, Tadayasu Sawaki, Kei’s true feelings and struggles are revealed as the story progresses. Kei is portrayed as a reserved and introspective individual who often hides his emotions beneath a calm and collected exterior. However, it is revealed that Kei is experiencing gender dysphoria, a condition that causes distress due to a discrepancy between one’s assigned sex and one’s gender identity. This revelation adds depth to Kei’s character, highlighting the internal conflicts and journey of self-discovery he undergoes throughout the series. In addition, Kei develops romantic feelings for Sawaki, adding to his emotional complexity.


Kei comes from a family that runs a sake brewery, creating a connection between their business and Sawaki’s family, who produce mold starters used in the brewing process. This connection serves as a plot device, facilitating interactions and shared experiences between Kei and Sawaki. While Kei’s family background is not extensively explored, it adds a layer of realism to his character and provides context for his involvement in the story.


In terms of physical appearance, Kei Yuuki is portrayed as an androgynous character in “Moyashimon”. This is consistent with his gender dysphoria, as he identifies more strongly with a female gender identity. Kei’s appearance undergoes a significant change when he presents himself as a girl in certain episodes of the series. This transformation is a visual representation of Kei’s journey toward self-acceptance and aligning his outward appearance with his inner identity.


While “Moyashimon” focuses primarily on the microbial world and the ability of certain characters to perceive and communicate with microorganisms, Kei’s abilities are not explicitly related to this aspect. Instead, his strengths lie in his emotional intelligence and empathy for others. Kei’s struggles with his gender identity and his romantic feelings for Sawaki demonstrate his resilience and ability to navigate complex emotional situations. His journey serves as a catalyst for personal growth, not only for himself, but also for those around him.


Kei Yuuki comes from the anime and manga series “Moyashimon” created by Masayuki Ishikawa. The series follows the life of Tadayasu Sawaki, a university student with the unique ability to see and communicate with microbes. Kei’s character plays a significant role in the narrative, helping to explore themes of identity, acceptance, and personal growth.

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Kei Yuuki – FAQ

Who is Kei Yuuki?

Kei Yuuki is a fictional character from the manga and anime series “Moyashimon”. She is a student in the agriculture department of a university and plays an important role in the story.

What is Kei Yuuki’s personality like?

Kei Yuuki is known for being intelligent, independent and determined. She is a hardworking and ambitious student who is passionate about her studies in microbiology. Kei is often serious and focused on her goals, but she also has a caring and supportive side.

What is Kei Yuuki’s role in “Moyashimon”?

Kei Yuuki is one of the main characters in Moyashimon. She serves as a mentor and guide to the protagonist, Tadayasu Sawaki, helping him to understand and appreciate the world of microorganisms. Kei’s expertise in microbiology and her dedication to her studies make her an invaluable resource for the other characters.

Does Kei Yuuki have any special abilities?

While Kei Yuuki doesn’t possess any supernatural or extraordinary abilities, her extensive knowledge of microbiology and her ability to communicate with microorganisms make her an exceptional character. She can see and interact with microorganisms, which adds a unique twist to the story.

What is Kei Yuuki’s relationship with the other characters in “Moyashimon”?

Kei Yuuki has a close friendship with the protagonist, Tadayasu Sawaki. She often acts as his mentor, helping him navigate the world of microorganisms. Kei also develops a romantic relationship with another main character, Haruka Hasegawa, as the series progresses. She also has good relationships with other characters in the series, such as Keizou Itsuki and Hazuki Oikawa.

Does Kei Yuuki have any significant arcs or character development?

Yes, Kei Yuuki undergoes significant character development throughout the series. As the story progresses, she becomes more open and expressive, which allows her to deepen her relationships with other characters. Kei also faces and overcomes personal challenges that further shape her character and add depth to her role in the story.