[I can not find the Jiangshi Cat outfit.]

Just an update for 2020...  I spent about 2 hours but eventually got all 3 pieces for the cat (outfit, hat, adornment).  The 3 Bloody Jianshies in the same area as the Stalker have dropped them for me.  Just kill one, move to the next, move to the next and go around in a circle like that a million times, and eventually you'll get them.  Good luck!

[The Red Mask for the mini Dungueon]

Hey just an update for 2020.  Furin does drop a red chest with the mask, still.  It just takes a long time and it took me 40 runs, one after the other.