Hope to get some serious advice from here to help if I can play this hand better.

25/50 HKD(about 4/8 USD) private home game in Hong Kong

Hero stack 400bb+ (20k+)
Villain stack 600bb+ (30k+)

Preflop: Hero opens $250 on UTG+1 with KK, all fold to villain on SB 3bet to 800,BB folds. I flat and we went headsup.

Flop:AcKs5c
Villain cbet 1300,hero calls

Turn:Js
Villain bet 2300,hero calls

River:7c

Normally I would say this is just standard call. However, that wouldn't be having this post.

Villain and I have a lot of playing history. We both are regular in that private game. We usually don't give up pots too easily to each other, and sometimes make big moves and play leveling games.

But today the dynamic was a bit different. There were 4~5 big fish(near to pure fish) in the table of 10 players in playing. So we both knew there won't be a need to make fancy play and level each other. Just wait for a hand then clean those fish stack,easy game as that. And we did clean them few times and fish have been keeping reload. We were the two biggest stack of the table.

Preflop thought: Since the table dynamic I noted. If I 4bet preflop then I was so sure villain would only call AKs,QQ+ and fold all the rest that he 3bet with for balancing range. Since I holded two Ks. AKs left with 2combo and his possible holdings are only QQ+. I don't think it's a very +EV situation to 4bet preflop. Therefore I flatted and play the flop in position.

Flop: Since his range is so narrow, I would say it must be better just calling his cbet then raising it. Because when you raise, you probably only get called by AA and AK. and AA has more combo than AK.

Seems I get a reason to fold this flop. But will you?

Turn: Js seems like a kind of dangerous card but it actually wasn't through my thought process started from preflop. I call his a-bit-more-than-half pot bet on turn for the similar reason as in the flop.

River thoughts?

Welcome to the forum, OP. Please don't include results (including your last action) in your posts, as they bias responses. I edit them out.

In a game this deep, iI guess I can see the PF flat of the 3-bet, given that we are in position.

Your thoughts on his range OTF are off, as you didn't 4-bet, so all of his "balance 3-bets" are still in there. The question is what does he have in his balancing range, and what, if any, of it c-bets on this board given the dynamic?

Turn really depends on the answers to the above, but I can't see folding after we've under-repped our hand so much.

River is really the same. Is there any FD in his flop/turn range? Is there anything other than value left in his range at all? Still, this under-repped against a thinking player, even given the current "stack the fish" dynamic, I can't see folding. Raising ever gets called by worse, so I'd make a crying call.