Suugaku Joshi Gakuen Ep 12

It's the final episode. What does everyone think about math now?

Nina is confused why her sister, Machida Kina, is here. Kina explains that she's here to fight Nina. Kina explains to Kazuki and Sayuri that Nina came to this school to find Kina and find out what happened to her after she became Math Boss. Nina is still confused and Kina says that she wants to rule over all the mathematicians in the world. (What? Why?) Kina wants to wipe out all the math schools using her position as Math Boss, even this one. Kina didn't want any mathematician to get in her way of ruling the world.

Nina is in shock. The sister she knew would never act like this. She would be so happy and excited about math, but the person she's looking at has dead eyes. Kina says it looks like she has to fight Nina and destroy her. Nina accepts the challenge and will defeat this impostor. Kina is so confident that she'll win that she tells Nina that this will be her last battle.

Team Nina and Kina are in a classroom, where Kina explains that the book she's holding holds 1200 years of math history, including 20,000 math problems that have been unsolved during all those years. Kina says that she'll choose a random unsolved math problem and Nina accepts. The problem Kina chooses is "Clearly prove that 1 + 1 = 2". Kazuki comments saying that everyone knows that answer is correct, but how would you go about proving it.

Kina tells Kazuki to call the start of the battle and he does. Kina immediately goes to the whiteboard and begins solving, while Nina is frozen, not sure what to do. She's never thought about this problem and she doesn't understand why she has to fight her sister. Her heart is really not in it to win this battle. Kina explains in fast forward how to solve the problem using Peano's Axioms, which uses number sets and a bunch of statements as support and definitions.  Sayuri and Kazuki don't see a flaw in Kina's explanation and Nina slowly begins to admit defeat.

Sayuri throws Nina a mentaiko bread, hoping that it will give Nina strength. Kazuki does the same. After Nina finishes eating both breads, Nina is back in full force. Kina freaks out a bit and is unsure how to continue her proof (and I thought she was done @.@). Nina continues the proof on her white board, defining that zero is the additive identity, which means that when zero is added to the number, that number will remain the same (just like 1 is the multiplicative identity).While she continues solving, they show a flashback of all of the episodes, showing how much Nina has grown. Nina finishes solving and ends it with Q.E.D, which is latin for "which was to be demonstrated" (this is usually written at the end of a mathematical proof).

Nina explains that math shows us how 1+1 = 2, but she feels that 1+1 can be equal to more than 2 because each new friend you have can be worth tens or thousands. Nina says that she's found true happiness in finding such dear friends. Kina collapses at how much her little sister has grown. Nina then says that Kina is way too early to challenge Nina and rule all the mathematicians in the world. Kina gives up and starts to laugh, saying that she made all this up to prank Nina. Then Nina remembers that her sister loved to surprise her. Team Nina was completely fooled.

Kazuki then asks where did Kina disappear to. Kina explains that she didn't disappear, she went to study in America as her reward of becoming the Math Boss. She was so excited that she left right away. Nina asks why didn't she contact her and Kina admits that she's not good with technology, just like Nina. When Kina came back from America, she heard that Nina was looking for her, so she decided to prank Nina and ask her old classmates to help her out (I guess she's referring to the Devil Sisters). Kina tells Nina that she's finally Math Boss and congratulates her, so does Kazuki and Sayuri.

Kina asks Nina where will she go to study now that she's become Math Boss since that's her reward. Nina refuses to leave this school and says that she likes it here. Kina says that it's so like Nina to say that and challenges her to a battle. But Nina says they already battled, but Kina says that she wasn't using 100% of her strength. (Oh really?) Nina accepts this math battle between sisters.

Kazuki then does a monologue explaining how he wants to continue going to this school and he's getting used to surviving amongst all the girls. You find out that Yuri picked Kazuki because she  just wants to protect him and his cute mannerisms. Sayuri, Mami, and Yuri all spot Kazuki holding a cartoon math book, which shows that he's really trying hard to study and understand math. Sayuri and Yuri both think that Kazuki is too dumb to get up to their level and Kazuki is frustrated that they don't believe in him.

The cartoon book that Kazuki is using to be better at math. 

It then cuts to the ref saying that there are no battles around, but she'll be ready to judge anytime. 

Fuyumi and the Gluttony girls happily eating away.

Shibuya Police Squad reporting that they'll always keep protecting peace at school.

Takako, Iroha and Miku drinking juice together. Takako and Miku notice that Iroha has been really nice lately.

Yuko, Tomoko and Satoko studying hard to reach Satoko's dream of the whole school becoming Inner Circle.

Tomoko asking her mirror who is the cutest of them all. The answer: Tomochi!

Comic relief girls (who adore Nina) vs Team mini-Nina: Battle of which group Nina likes better.

Nina screams that she's done it, which gets everyone's attention. She's proven Rosenzweig's Demonic Function, which is thought to be the most difficult problem that would take until the end of the world to solve. Nina says that she'll tell Mami, Yuri, Sayuri and Kazuki how she solved it, but then ends up saying that it would be impossible because there is not enough time. The four get slipped up by this, but Sayuri says that is why she loves Nina so much.

The episode ends with Nina, Sayuri, Mami and Yuri doing the famous Sine, Cosine, Mentaiko move, while Kazuki does his best to keep up. That's the end of Suugaku Joshi Gakuen!

I would like to say thanks to Up-Front for making such an interesting drama series, MM-BBS & Kirarin Snow for working so hard on the English translations and the Hello! Project Facebook fanpage for uploading the videos for everyone to enjoy. 

There wasn't  much I could say after episode 9 because it got into math theories and proofs that I've never heard of before. ^_^" I liked how this series always balanced fun and tense situations, and it was overall very happy and positive at the end. Just like the progression of math in this series, the higher you go up in math, the less numbers there are to deal with because it becomes a lot more theoretical than practical. I hope everyone enjoyed this series involving math, and maybe some of you will like math a lot more than you did before.