Chaprun is the watery stage of Fantasy Zone II. It has the distinction of being the only stage where all of the bases are either at the top of the screen, or the bottom. While this seems like a distinct advantage, don't let your guard drop for one second. There are two shops here, along with a third secret shop, so you'll want to spend your money wisely. As it turns out, this is the first stage where you can purchase the Twin Big Bombs. If you buy these, you'll no longer have to choose between the power of Big Bombs, or the frequency of Twin Bombs.
The bases in Chaprun are called Haihon. As mentioned earlier, this is the only stage where you will find every base of a section either at the very top of the screen, or the very bottom. At first, this seems to make the stage easier; all you have to do is stay at the top or bottom, and clear each base away. However, the enemies will make sure that you have a hard time staying in one place for a very long time, and force you to move around. You'll also have a harder time bombing the bases at the top unless you get very close to them, so be careful.
Arbors fly out from the Haihon bases. They appear from the base and pause briefly, before relentlessly pursuing Opa Opa. Do not stay in one place for very long when they are around. Clear them away before resuming your attacks on the bases.
Bikoro are multi-colored orbs that zoom across the screen, and are gone almost as quickly as they appear. They cross the screen in a giant arc. Hitting all six of them for the $200 coin is difficult to do, it's safer to simply avoid them.
Krungs look like green mushrooms that appear on the screen in formation, three on top and two below. They start out flying fast, and may appear to overtake you, but if they slow down enough and remain on the screen, they can boomerang back to attack you a second time.
Six Rako fall down from the top of the screen, and bounce along the bottom of the screen. Once they start to bounce, they may pick up some momentum and start bouncing around in Opa Opa's direction.
The boss of the fifth stage is called Buubuuman. This boss is actually surprisingly easy for this late stage of the game. All he does is shrink and grow, and he is only vulnerable to attack when he is at his fullest size. No projectiles are fired at you during the entire attack, so you only have to avoid getting hit by Buubuuman, who moves to your location whenever he starts growing again. Move out of the way, and into a position where you can attack for the brief period when he is full size, and then repeat the process until he is defeated.