This band won't be indies anymore after the thirtieth of August, BUT!!! If you're looking for really good bassists in Japanese bands, here is my favorite, the dude actually knows how to play his instrument:
YouTube - 摩天楼オペラ Matenrou Opera - "Yo's solo" LIVE
YouTube - Matenrou Opera (摩天楼オペラ) - 電脳パラノイア *listen at 2:03 so you can hear the bass solo
YouTube - Matenrou Opera - Datura [ダチュラ] *put on headphones/earbuds and start listening at around 2:37
To be honest, you should listen to most of the bands' music, since the bass is amazing.
Another indies band that "has" a good bassist and started just last year in November would be LIX. The reason why I say "has" is because it's just a support bassist for their live shows, I don't know if he's the one playing when they record their music.
YouTube - LIX. - Re:vive