Why on earth is niwatazumi tagged here? As far as I can tell, even in the twitter post, it doesn't seem like he's involved. I'm gonna go ahead and remove it.
Kaga-san, why?HonestIt was no good.Why does Kaga-san's CD...STOP!!Why?Cost so much money online?STOP THE NATIVE GIRL!!
Kaga-san!!Because they can sell at a high price.
Possibly related to Mizuki Shigeru's quote in this TV program:
Q: "Why do you keep drawing youkai art/manga?"
A: "Because they sell well."