{{Lyrics
| group         =[[IOSYS]]
| group_en      =
| titlejp       =チルノのパーフェクトさんすう教室 ⑨周年バージョン
| titlerom      =chiruno no paafekuto sansuu kyoushitsu kyuu-shuunen baajon
| titleen       =Cirno’s Perfect Math Class, ⑨th Anniversary Version
| length        =
| arranger      =[[ARM]]
| lyricist      ={{夕野ヨシミ}}
| vocalist      =IOSYS{{lang|ja|と愉快な⑨周年フレンズ}} ([[IOSYS]]+[[幽閉サテライト|Yuuhei Satellite]]+[[A-One]]+[[豚乙女|BUTAOTOME]]+[[COOL&CREATE]]+[[TaNaBaTa]]+Alternative ending)
| other_staff   =
| source        =
*original title: {{lang|ja|おてんば恋娘}}
*source: {{EoSD}}
| eng_only      =
| untranscribed =
| unromanized   =
| untranslated  =
| album1        ={{LyricAlbum|東方氷雪大感謝|IO-0311.jpg}}
| lang          =
| kan1          =
「みんな～！チルノのさんすう教室、⑨周年だよ～！アタイ大学⑨年生！天才を、極めたよ～！」
| kan2          =
「留年じゃねーか？」
| kan3          =
ギリギリ　綱渡りで
ドキドキ　一か八かで
単位と卒論　なんとかして卒業
出席日数　ちょっとたりない {{lang|en|GO GO!!}}
| kan4          =
バーカバーカ　バーカバーカ　バーカバーカ
「口を開けばバカバカってうるさいわね！」
バーカバーカ　バーカバーカ　バーカバーカ
「そーゆうのを『バカの一つ覚え』っていうのよ！」
バーカバーカ　バーカバーカ　バーカバーカ
「何よもう！バーカ！バーカ！」
バーカバーカ　バーカバーカ
| kan5          =
紅魔館から　月ロケットが
秒速⑨万キロで飛び立った
白玉楼で　二人降りて
半人乗る暇もない
八雲さんちが　対抗意識
迎撃用のミサイルブッぱったー！
| kan6          =
助けて助けて　えーりんえーりん
ムリムリ咲夜にブン投げ！
時間操作で　トゥルーエンド
| kan7          =
山落ち　意味など無いさ
全ては　心の中
幻想郷の中心で
「１・２・⑨！」
| kan8          =
くるくる　宇宙の闇
ぐるぐる　地球回る
そうよ　つぶら目玉　ふたつとも狙うの
きゅっとしてきゅっとして　どっかんかーん
| kan9          =
次々　問題でる
まだまだ　追試続く
凍る　部屋の中
ひんやりした温度も時間も気にせず
「ゆっくりしていってね！」
| kan10         =
バーカバーカ　バーカバーカ　バーカバーカ
「カバディカバディカバディカバディ！」
バーカバーカ　バーカバーカ　バーカバーカ
「バカディバカディバカディバカディ！」
バーカバーカ　バーカバーカ　バーカバーカ
「もうみんな爆発しちゃえばいいのよ！」
バーカバーカ　バーカバーカ

| rom1          =
“minna! chiruno no sansuu kyoushitsu, kyuu-shuunen dayo! atai daigaku kyuu-nensei! tensai wo, kiwameta yo!”
| rom2          =
“ryuunen janee ka?”
| rom3          =
giri giri tsunawatari de
doki doki ichi ka bachi ka de
tan’i to sotsuron nantoka shite sotsugyou
shusseki nissuu chotto tarinai GO GO!!
| rom4          =
baaka baaka baaka baaka baaka baaka
“kuchi wo hirakeba baka baka tte urusai wa ne!”
baaka baaka baaka baaka baaka baaka
“soo yuu no wo ‘baka no hitotsu oboe’ tte iu no yo!”
baaka baaka baaka baaka baaka baaka
“nani yo mou! baaka! baaka!”
baaka baaka baaka baaka
| rom5          =
koumakan kara tsuki roketto ga
byousoku kyuuman kiro de tobitatta
hakugyokurou de futari orite
han’jin noru hima mo nai
yakumo-san-chi ga taikou ishiki
geigeki-you no misairu buppattaa!
| rom6          =
tasukete tasukete eerin eerin
muri muri sakuya ni bun’nage
jikan sousa de turuu endo
| rom7          =
yamaochi imi nado nai sa
subete wa kokoro no naka
gensoukyou no chuushin de
“ichi. ni. kyuu!”
| rom8          =
kuru kuru uchuu no yami
guru guru chikyuu mawaru
sou yo tsubura medama futatsu to mo nerau no
kyutto shite kyutto shite dokkan kaan
| rom9          =
tsugi tsugi mondai deru
mada mada tsuishi tsudzuku
kooru heya no naka
hin’yari shita ondo mo jikan mo ki ni sezu
“yukkuri shite itte ne!”
| rom10         =
baaka baaka baaka baaka baaka baaka
“kabadi kabadi kabadi kabadi!”
baaka baaka baaka baaka baaka baaka
“bakadi bakadi bakadi bakadi!”
baaka baaka baaka baaka baaka baaka
“mou minna bakuhatsu shichaeba ii no yo!”
baaka baaka baaka baaka

| eng1          =
“Hey everyone! It’s the ⑨th anniversary of Cirno’s Math Class! I’m in my 9th year of university now! I’ve taken my genius to the next level…!”
| eng2          =
“Haven’t you just repeated the same class?”
| eng3          =
It’s so close! Just like tightrope walking.
Thump-thump! The stakes are high.
Through credit and a thesis, I’ll graduate somehow
But my attendance isn’t quite high enough. ''Go, go!!''
| eng4          =
Idiot, idiot! Idiot, idiot! Idiot, idiot!
“You just open your mouths to call me an idiot. How annoying!”
Idiot, idiot! Idiot, idiot! Idiot, idiot!
“They say ‘he that knows little often repeats it,’ you know!” <ref name="one" />
Idiot, idiot! Idiot, idiot! Idiot, idiot!
“What the hell?! Idiot! Idiot!”
Idiot, idiot! Idiot, idiot!
| eng5          =
A moon rocket flew from the Scarlet Devil Mansion
At a speed of 90,000 km/s.
Two people got off at Hakugyokurou.
There was hardly time for half-humans to ride.
That Yakumo lot are so competitive—
They fired off an interceptor missile!
| eng6          =
Help me, help me! Eirin, Eirin! <ref name="two" />
It’s no use! Sakuya, throw something!
Time manipulation causes the true end.
| eng7          =
No peak, no climax, no meaning. <ref name="three" />
Everything lies within one’s heart.
In the heart of Gensokyo…
“1, 2, ⑨!”
| eng8          =
Whirling around in the darkness of space,
Round and round, the world turns.
That’s right—I’ll aim at a pair of round eyeballs.
I’ll squeeze them and squeeze them, and then *crash*
| eng9          =
The questions come one after another.
There are still more exams!
Inside this frozen room,
Don’t worry about the cold or the time:
“Take it easy!” <ref name="four" />
| eng10         =
Idiot, idiot! Idiot, idiot! Idiot, idiot!
“Kabaddi, kabaddi, kabaddi, kabaddi!” <ref name="five" />
Idiot, idiot! Idiot, idiot! Idiot, idiot!
“Bakaddi, bakaddi, bakaddi, bakaddi!”
Idiot, idiot! Idiot, idiot! Idiot, idiot!
“I should just go and blow everyone up already!”
Idiot, idiot! Idiot, idiot!
| eng11         =
In Reimu's money box, someone has stole the money
Eintei's Eirin came looking for the culprit (Eirin! Eirin!)
A verified security video of the crime
Fingerprint collecting & insect collecting
| eng12         =   
Yes yes, and the case was closed
Because nobody put anything in the money box in the beginning
|eng13          =
She's a genius behind common sense, 
and has an IQ of ⑨
Counting the prime numbers in order,
1, 2, ⑨!
| eng14        =
Laughing foolishly, laughing loud
Wanting to play more, there's still not enough
The ⑨ years have flew by like a flash, but it's true
| eng15         =
You'll have ⑨ billion views if you're a worldwide idiot
If you ask me, it's peaceful
Good job, server management!
|eng16          =
You keep making fun of me like this.
Don't you even know there's a difference between idiots and geniuses?
You're really just too much!
In my case, I might just be an idiot for a long time! "Idiot idiot!"
|eng17          =
Every, every, every, every,
Every, every wisdom
Even if you gather, gather, gather, gather it
My, my, my, my,
My, my strong
Head, head, head, head can't be matched by you
Breakfast, breakfast, breakfast, breakfast,
Breakfast, breakfast, after that I
Twist, twist, twist, twist,twist, twist a baby's hand
I'm, I'm, I'm, I'm,
I'm, I'm flawless
What is called, what is called, what is called, what is called perfect
⑨ hundred billion trillion thousand good!
|eng18          =
No peak, no climax, no meaning.
Everything lies within one’s heart.
In the heart of Gensokyo…
“1, 2, ⑨!”
| eng19          =
Whirling around in the darkness of space,
Round and round, the world turns.
That’s right—I’ll aim at a pair of round eyeballs.
I’ll squeeze them and squeeze them, and then *crash*
| eng20          =
The questions come one after another.
There are still more exams!
Inside this frozen room,
Don’t worry about the cold or the time:
“Take it easy!”
|eng21           =
Idiot, idiot! Idiot, idiot! Idiot, idiot!
"⑨ years and you're still saying the same thing, how?"
Idiot, idiot! Idiot, idiot! Idiot, idiot!
"Now that's what I call being an idiot!"
Idiot, idiot! Idiot, idiot! Idiot, idiot!
"What the hell?! Idiot! Idiot!"

| lyrics_source =[https://releska.wordpress.com/2017/09/25/cirnos-perfect-math-class-9th-anniversary-version/ Translation] by [https://releska.wordpress.com/ Releska]
| notes         =
== Notes ==
{{Reflist|refs=
<ref name="one">By using this proverb, Cirno implies that her tormentors are dumber than her because they say the same thing over and over.</ref>
<ref name="two">This refers to the [[COOL&CREATE]] song ‘[[Lyrics: Help me, ERINNNNNN!!|Help me, ERINNNNNN!!]]’</ref>
<ref name="three">The Japanese lyrics are a contracted form of {{lang|ja|山もない落ちもない意味もない}} (yama mo nai ochi mo nai imi mo nai). This is where the word ‘yaoi’ stems from (<u>y</u>ama, <u>o</u>chi, <u>i</u>mi)</ref>
<ref name="four">This is a reference to the ‘[[Yukkuri shiteitte ne!|yukkuri]]’ meme, which involves Touhou characters depicted as giant heads. The phrase can also be translated as “do it slowly.”</ref>
<ref name="five">Kabaddi is a form of contact sport originating in India. Chanting “kabaddi” is an important part of the game. ‘Bakkadi’ is a corrupted form of the title that also fits in {{lang|ja|バカ}} (baka – idiot).</ref>
}}
| extra_info    =The arrangement was released ([https://www.youtube.com/watch?v=9iI0-OdRzHI Official Music Video]) on [[Cirno]] Day (Sept 9<sup>th</sup>, 09/09) to celibrate the 9th annaversery of [[Lyrics: チルノのパーフェクトさんすう教室|Cirno's Perfect Math Class]]
}}