I don't think Hikki looks fat in those pictures. Sure she's not a toothpick, but she's nowhere near fat
Whenever celebrities gain a couple pounds these days everyone's always "OMG THEY GAINED 40 POUNDS" when they actually needed to put on some more weight in the first place..
But Ayu doesn't look like she gained weight on the MS blog thing..and to be honest, in that performance, it looks like she sort of gained muscle. But, who knows.