What Does "Seiso" Mean?

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Get the low-down on the most common VTuber slang

Co-authored by Janice Tieperman

Last Updated: March 13, 2024 Fact Checked

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Seiso Definition

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What is a seiso VTuber?

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Seiso Origins

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Other VTuber Slang

“Seiso” is a popular slang term used within the Virtual YouTuber (VTuber) community, especially among popular streamers. Based on “清楚” (seiso), the Japanese word for “clean” or “tidy,” this word has evolved to mean “wholesome” or “pure” in terms of a VTuber’s onscreen persona. Although it has its roots in meme culture, “seiso” and its opposing term, “unseiso,” have become well-established ways to label and categorize VTubers. Read on to get the inside scoop on this slang term (along with other VTuber lingo).

Things You Should Know

“Seiso” (清楚) is a Japanese adjective that means “clean” and “tidy.”
It was co-opted by the Virtual YouTuber (VTuber) community to mean “wholesome” or “pure.”
Seiso is used as a label for wholesome VTubers, though it’s always used to meme about VTubers who are definitely not pure or wholesome.

Section 1 of 4:

Seiso Definition

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Seiso officially means “clean” in Japanese. Spelled in kanji as 清楚, seiso is an adjective (descriptive word) that means “trim,” “neat,” “tidy,” or “clean.”^{[1]
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Research source} It was repurposed by the Virtual YouTuber (VTuber) community to mean a pure and wholesome streamer, but is often used as a tongue-in-cheek way to tease VTubers who definitely don’t fit this definition.^{[2]
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- VTubers are streamers who create content using a virtual, anime-style avatar (rather than showing their face on camera). VTubers often adopt a specific persona for their characters, and even come up with in-depth backstories for them. They typically stream on Twitch and/or YouTube.

Section 2 of 4:

What is a seiso VTuber?

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A seiso VTuber has a wholesome, pure, and family-friendly image. By the original definition, a seiso VTuber has a “clean” image—they act very innocently on-stream, and they don’t engage in any adult humor. VTubers are often categorized by the binary of being either seiso or “unseiso” (not entirely wholesome/innocent).^{[3]
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- Well-known seiso VTubers: Ninomae Ina’nis, Uten Hiyori, Tokino Sora, Rosemi Lovelock

Section 3 of 4:

Seiso Origins

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Seiso was made popular by VTubers Dennou Shojo Siro and Tsukino Mito. Siro (a VTuber who debuted in 2017 with the .LIVE agency) first coined the term “seiso” in an ironic way within the VTuber vernacular, and Tsukino Mito (a VTuber who debuted in 2018 with the NIJISANJI agency) helped popularize the use of the word. Both of these characters are definitely not seiso in a wholesome way, but in a tongue-in-cheek way.^{[4]
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- Tsukino Miko in particular is known for requesting her fans to create mature, adult-oriented art of her, which definitely isn’t a “seiso” thing to do.^{[5]
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Section 4 of 4:

Other VTuber Slang

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An ironic term that means someone is both unintelligent and vulgar. The term was coined in a stream featuring Takanashi Kiara (a VTuber with the HoloLive agency) and her fellow HoloLive VTubers. In the video, Kiara was jokingly placed in the “bottom left” quadrant of a purity alignment chart, which represented people who were both stupid and impure.^{[6]
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A VTuber’s debut refers to the day they first start streaming. Debuts are often advertised heavily (especially by agency-based VTubers) to generate hype for the character’s streams.^{[7]
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A VTuber’s graduation refers to their last stream before their character goes into retirement. As the final stream, it generates a lot of hype and fanfare among viewers.^{[8]
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A Japanese cuss word that’s used in playful banter from Japanese-speaking VTubers. For example, a VTuber might say "kusoge" to mean "stupid game" during a frustrating moment on stream.^{[9]
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Research source} Chances are, a truly seiso VTuber won’t use this term very much.
A VTuber who revolves their brand around more mature, NSFW (not safe for work) content.^{[10]
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