Stay in a corner and watch for the flashlights. All the guards in the Mizuki will have a flashlight in hand searching for you. Either you can wait until one is close enough that you can swerve around civilians and melee kill him or, if you have a clean shot, give 'em the 1-2-3. The shooting in K&L is crazy "realistic" what with the recoil sending your aim up half an inch after you fire so start at the stomach and fire thrice. Stomach, chest, head. Then regain cover until the guards stop coming your way. At this point, you move slowly and unexposed until you get their attention. Once you make it to the bar, jump over, grab the grenade by the drinks for later use or the lulz, and use that cover. Repeat until you've gone up a floor or two. Eventually, you'll be where the civilians just aren't around and after a few more checkpoints, ding. It'll pop up for 'ya. Just gotta be patient and find good cover.