OP, you're new here, so let me just tell you that masaegu and supperman are both native Japanese speakers, and I think siokan is, too. I'm about 99% sure. I know he's in Japan, English is not his native language, and his Japanese is excellent. I just don't remember seeing him say "I am Japanese," so I'm only 99% sure.
In any case, listen to them about this question more than you listen to me.