profoundly giftedという言葉を知っているかい？　天性の知能レベルを備えた超天才児のことだよ。適切な環境にさえ置けば十歳そこらで大学を卒業する。自殺した女の子も、そんな選ばれし人間の一人だった。
望月まどか。三重県津市出身。12歳。8歳の頃に東京大学に入学し、翌年には主席卒業。二十一ヶ国語を話し、現代学問のほぼすべてを網羅する。
言葉にするのは簡単だが、俺を含めて彼女の考えを理解する人間なんていないだろう。きっと"彼女が見ている世界は、俺たちのそれとは違う"のだ。天才と変人は紙一重とよくいうが、パブロ・ピカソがある日を境に多角形で人物を書いたのと同じように、生前の彼女はとにかく、とち狂っていたらしい。
壊れたプレイヤーのようにひたすら呪文を繰り返す。全く理解できない形や色を紙面に展開する。凡人が傍から見る分には知識障害者との違いなんてこれっぽっちもない。そもそも彼女の会話に合わせられる人間がいない。
彼女が他の人間と意志疎通する行為なんて、言い換えれば人間が鳥に話しかけるようなものだ。彼女にとって自分以外の全ては自分より劣る何かで、命はどこまでも軽く、世界は客観的に眺める程度でしかない存在なのだ。もちろん、交友関係も皆無。
だが、そんな彼女にもいまだ体験したことのない学問があった。それは死の概念だ。彼女は次第にのめりこみ、世界中のありとあらゆる死の資料を集め始めた。俺も彼女のスクラップを見せてもらったが、愕然としたよ。雨の中でトラックに轢過されたもの。両手足がバラバラに分解され間違った場所に再接続されたもの。顔面が黒く焼けただれて変形した金髪の女。眠るように凍死する少女……。
最終的に彼女はもっと間近で死を見たいがために、包丁を片手に夜な夜な街へと繰り出すこととなる。自転車にまたがってね。げに恐ろしい世界最年少連続猟奇殺人犯の誕生ってわけだ。だが、それでも彼女の知的好奇心は収まらない。彼女にとっての自分以外とは、人間ですらない下等生物ということを考えれば当然か。彼女が本当に満足するには、人間を殺すしかなかった。つまり、自分のことさ。
……ところで。彼女が机の上に残していった遺書のコピーがあるんだ。というより、日記のようなものだがね。……よかったら君、見てみるかい？　素敵な夢を約束するよ。

Do you know the expression “profoundly gifted?” It refers to genius children who naturally have an extremely high level of ability. If they are given an appropriate environment, they can graduate from university at around 10 years of age. The little girl who committed suicide was one of these children.
Her name was Mochizuki Madoka. She was born in Tsu City, in Mie Prefecture. She was 12 years old. Entering Tokyo University at age 8, she graduated the next year at the top of her class. She spoke 21 languages, and had an exhaustive knowledge of almost all of modern learning.
It's an easy thing to say, but there probably wasn't anybody, including myself, who could understand the way she thought. The world that she perceived must have been so different from the one we see. It's often said that “genius and insanity are two sides of the same leaf,” and just as Pablo Picasso one day decided to draw humans with polygons, she was apparently quite manic during her short life.
Constantly repeating magic spells like a broken record player. Writing completely incomprehensible shapes and colors on a piece of paper. For ordinary people, this sort of behavior is exactly the same as that exhibited by mentally-challenged people. But there was nobody capable of following her in a conversation in the first place.
For her to take action to come to a mutual understanding with other humans would have been like, to put it differently, a human trying to speak to a bird. For her, everything apart from her was something inferior, something bearing life lightly, incapable of existing and looking at the world in any other way than objectively. Of course, she had absolutely no friends.
However, there was an area of study that she hadn't yet experienced. That was the concept of death. She gradually became more and more preoccupied with the question, and started gathering materials on death from across the world. I had her show me her scrapbook, and I was shocked. There was somebody that had gotten crushed by a truck in the rain. Somebody who's hands and feet had been amputated and then reattached in the wrong places. A girl with blond hair whose face had been burned until it turned black and was grotesquely crumpled. A young girl, who, having frozen to death, looked like she was sleeping.
In the end, in order to be able to see death closer-up, she took to wandering the streets at night with a knife in her hand. She rode on her bicycle. It was the terrible birth of the youngest serial killer in the world. However, none of this still satisfied her intellectual curiosity. This is probably obvious; if her thoughts were that everybody apart from her was an inferior life form not worthy of being called a human. To really be satisfied, she had to kill a “human.” In short, she had to kill herself.
...In any case, there is a copy of the dying message that she left on top of her desk. Actually, it's rather more like a diary... If you want, why not take a look at it? I guarantee you pleasant dreams.