There are two songs i really want to buy on Itunes but they arn't there. why?

The songs are "Take off" by 2pm and "Core pride" by Uverworld. They are both japanese bands and i've seen other japanese songs so i dont know why these two arn't available. And there is another one "Monochrome no kiss" by SID. again a japanese band. these are good songs and they arn't available. HELP!