Help finding an anime

So my mother is tying to remember an anime she thinks she saw, it might be a hallucination or dream but here are the details if you find anything similar please let me know

- modern setting

- protagonist has long white hair, adult slender, swordsmen, hunter or assassin

- small kid latched onto them and moved in with them, is independently wealthy, colored hair,

- side character is a woman in black strapless top leather pants, either had cool car or motorcycle

-near the end of the series cut up a bunch of grunts in a long hallway