Reply for Puchotek :
This is just my random guess but I think it's because Japan national football team wear blue uniform so they some way or another have pride about the colours. \\ok stop stupid me. Maybe people can point out whether there are some historical values in it?
Anyway, let's see where this is going. I have love-hate relationship with Aoiro Ping-Pong. At least I hope this one doesn't disappoint me.