I wasn’t planning on playing this game anymore for a while, but after reading this I realized I had completely forgot to mess around with K’. So I hit the training mode and quickly deduce that the japanese guy did:
Low D, OTG low B~A chain xx ein trigger xx slide, glasses super.
It does exactly 140 dmg, but the problem is it requires counter hit to get that much (like the combo on KOFcolumbia). It does 98 dmg without counter hit. Correct me if I’m wrong on the combo though.
Anyway, after fiddling with K’ for like… a minute this is the most optimized combo I could find:
Low D, walk up OTG lowB~A, walk up OTG low B~A, OTG standing B~B xx qcf+A~slide, qcf,hcb+A/C
113 damage without counter hit, 164 with. The combo’s actually kinda hard to do so you could just elimate one set of low B~A’s and not have to do the whole walk up business.
I’ve actually accidentally got those a few times also. I haven’t really tried messing with it yet since I devoted all my time to finding the characters with the best OTG games. 
More notes: Though I haven’t messed with wall combos extensively, I found that having your back all the way against the wall tends to prevent combos more than anything else. Since the wall is right there any sort of launcher will cause them to immediately hit the wall and drop straight down. A large number of the standard combos I found won’t work against someone with their back against the wall. When the opponent hits the wall they stumble forward and become much shorter, causing hits to go over them. Also, when you hit them against the wall enough times (I think three?) they become airborne. Again, since the wall is right there they drop straight down and as of right now I haven’t really found any ways to really capitalize on that.
Lastly, hit stun is increased on crouching opponents, which allows for combos not normally possible otherwise. Again, I haven’t really messed with this much, but K’s low B~A chain doesn’t combo on standing opponents… but it does on crouchers.