Can u give me the name of this song Dx ? JDrama LoveGame?

First of all, sorry if it is in the wrong category.
So, there's this youtube video promoting the show "LoveGame".Link :
http://www.youtube.com/watch?v=lTGPFlWt2gQ

All i want to know is the name of the song, playing in the first 3
minutes ,a download location would be good too .