I remember getting Koffin KK, it's Shujinko's Hara Kiri.
[EDIT] In case you didn't know, his Hara Kiri is in Earthrealm A-8 in the small cave at a random time on the 16th of the month.

from my thread almost on page 3 now- found MO:
"thanks to ScorpioKang for the location- but he wasn't sure on time or date or anything- well, this is when I found it: in Chaos on the 17th section D-7 when you arrive the hut on the right side at 12am Monday, there's actually 3 huts on D-7 two on the right one on left. It's the 2nd one on the right from arrival point. and may that be the last thing I need in chaos- 'cause I hate that place..."

BH is the Liu Kang Tomb arena, it can be found at the opposite end of the bridge from Jax in Earthrealm at 6 a.m.
MO is the Dragon King Temple arena. It is in Chaos Realm, at D8 in a hut.
I've unlocked MM, but can't find it in my notes, and I haven't unlocked KK.

Thanks everyone for the help. I'll go after them right now.

I got BH and MO thanks to your info. I just hope someone knows where MM and KK are. I'm betting that MM is Shujinko 2nd Alt. costume.

GoddessofLight pointed out where KK was, earlier in this post. I went and got it myself. As to MM, do you have all of Shujinko's moves? I didn't mark what coffin a couple of them came out of, and I have MM unlocked (I can't believe the game won't let you open already unlocked coffins!).