Puzzle 031: Growing Paper

ナゾ０３１　紙で育つ
それあ最初、指先ほどの大きさだった。
しかし私が紙を与えると、それはみる
みるうちに大きく育っていった。
怖くなた私が何も与えないでいると
次第に小さくなっていき、やがてその
姿を消してしまい、二度と現れることは
なかった。
私が何を育てていたのかわかるかい？
ひらがな１の文字で答えてごらん。

Google Translate
Oh first it was the size of a fingertip. I give the paper, but it went out Mirumiru growing larger. Iki has been reduced gradually 怖Kunata not give me anything, it eventually disappeared away, it did not appear again. Kai know what I was raised what? Look one answer hiragana characters.

Notes on Puzzle
The image is of some kids sitting around talking; there is a pile of paper and books in the center of them. You have to figure out how the paper can act in a certain way: At first it was very small (the size of a fingertip), then it grew large, then it shrank and disappeared, and it did not appear again. The answer is a single hiragana.