Vanishing Tic-Tac-Toe

This game is similar to well-known game, Tic-Tac-Toe: that two players put mark by turns and make a line consisting of three own marks.
But in this game, when you put the fourth mark, the first mark vanishes. And when the fifth, the second does.
So players should put mark by thinking well.
You can play with both computer and man.

sound effect : http://maoudamashii.jokersounds.com/music_se.html