Actually, I know this beautiful Japanese song from a friend who was asking for the title of song in a drama called "Friendly Fire" (法網追擊). At first, I don't know, either. So, I did some searches on Google and found that it's a song by Tamaki Koji (玉置浩二). This nice Japanese song is called 'Friend'. It's used as the song in that Hong Kong TVB drama as the Japanese theme song.
Well, let's enjoy this nice song.