Artist's description:
After the appearance of this bastard child, Marisa cut all ties with Reimu after a bitter legal battle where she got out of paying child support, using the obvious defence that she was a woman too and could not possibly have been the father.

This left Reimu a bitter, broken woman whose carefree lifestyle was suddenly disrupted by this unwelcome burden.

Due to her neglect, her girl grew up with the worst traits of both parents -- the thuggish manner of Reimu and the criminal tendencies of Marisa, and spends her days terrorizing the human population of Gensokyo, stealing from her mom's osaisen box, and smoking opium.

That's a cleverly put together bike.

Not so much with the name, though: "Saite(i)" just means "the worst".