The stage 2 boss of Touhou 6: EoSD. The only stage 2 boss to ever get that much screen time. Arguably the strongest in all of Gensokyo.
If one is attacked by Cirno, the best defense is to talk calmly to her, and ask her a riddle. No matter how easy the riddle, there will be enough time to flee while she tries to figure out the answer.
by seventhfonist425 May 12, 2011
An ice fairy first appearing in the 6th installment of the Touhou series, "Embodiment of Scarlet Devil".

Words like "stupid" or "fool" can be replaced by "Cirno".

But disregard all of that, all you need to know about Cirno is ⑨.
"I'm the strongest!", said Cirno.
by Riboflavinbob January 15, 2009
person a: do you know cirno?
person b: no, who is she?
person a: the STRONGEST
by Aem64 January 19, 2022
⑨ /⑨ /0⑨ , also known as ⑨ day, but more commonly used to refer to the day Cirno became supreme overlord of our planet, solely because she is THE STRONGEST IN ALL OF Gensokyo. CIRNO IS OUR OVERLORD. HAIL CIRNO.
Touhou fan #1: ⑨ /⑨ /0⑨ was the greatest day in history.
Touhou fan #2: Yeah, ⑨/ ⑨ /10 and ⑨ /⑨ /11 can never compare. Although they're pretty nice, the anniversary of our strongest overlord is quite a ⑨ ish event, you know.
Touhou fan #3: Happy Cirno Day, bakas! *spams danmaku*
Everyone: *dies* @_@
by Daiyousei September 9, 2011
Heh, Cirno Day and me birthday are ⑨/⑨/x⑨. Hehefunni
by Strepto November 19, 2019