“Kourin” (香霖(こーりん), Kōrin) is the canonical nickname for Rinnosuke Morichika in Touhou Project, though it has a rather storied history in the Japanese fanbase as a derogatory nickname since his character wasn't widely known until Touhou Kourindou's first anthology released in 2010.

The first chapter of Touhou Kourindou was published in January 2004, where we see that Marisa often uses “Kourin” (香霖) as a nickname for Rinnosuke. Due to his full name containing archaic kanji that Japanese IMEs rarely recognize,¹⁾ some members of the Japanese community would adopt “Kourin” (こーりん) as a nickname for Rinnosuke in order for them to get around the aforementioned issue.

On February 1st, 2005 at 23:20(11:20PM) JST, a traditional sketch of a muscular Rinnosuke with a loincloth had been uploaded for the Rinnosuke vs. Reisen match of the 2nd Touhou Saimoe Tournament.²⁾ He lost, but it was expected as he wasn't common knowledge³⁾ and fans treated him as a joke, creating a bizarre, muscular man who is perverted, but short-sighted and makes easy mistakes.

The joke eventually died out after the Touhou Kourindou anthology was released in 2010, cheap jokes that demean characters were now met with scorn, and the fan creation became a thing of the past unless you intentionally want replies. In the west, this iteration of Rinnosuke was dubbed “Mannosuke” for his muscular physique,⁴⁾ but suffered a similar demise as Western fans met it with scorn as well.

• Perverted Kourin on Pixiv Encyclopedia
• Kourin on Niconico Encyclopedia

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