"Skittles" is actually the song "CandyPOP" by Heartsdales, which is the quintessential Japanese rap band and I suggest you start there if you want to delve into the sub-genre.
And while this isn't a band, per se,
Hyadain makes some great video game related raps that are in Japanese as well.
I'm not all that well versed in Japanese Rap/Hip Hop (my J-music tastes skew toward the more alternate) but these are some artists that I like that fit what you're asking for.