Starting in a forest, the first enemies you encounter are some ninjas. These enemies will throw shurikens at you and can also jump straight upwards. A slightly stranger enemy is encountered not that far into the game, who takes two hits to kill and will shoot at you with a dart when attacked.
Some ninjas will just drop down from above, but they are slow to attack and you should be able to kill them before they get to do anything. Towards the end of the outdoors section, some kunoichis will appear. These ladies jump up and then use a sword to stab down.
Upon entering a cave, you will find some large samurais. These use their swords to block your shots, and will release a powerful ground projectile wave at you. You can block this wave, and then fire back at them whilst they are still exposed. It takes the samurais a few seconds to recover from using their projectiles. The final samurai is the game's first sub-boss, who takes more hits than the others. His projectile also has a boomerang effect, so be ready to jump or block it.
The next section takes place in a larger cave, and you'll get the chance to use many of Joe's new abilities here. Hold up and press the jump button to grab onto any lines you come across, and use them to move across pits. Throughout this stage there are many ninjas to fight.
In some parts of this cave you will have to use the off the wall jump to move upwards. There is also a part where you will have to either time some jumps or carefully move across the floor, as spikes will keep popping out.
The samurais make their return, but are defeated in the same way as before. Use the second rope line to move across another pit, and head right to fight the first boss.
The first boss is a monster samurai, armed with two swords and a spear. He can block shurikens thrown at him, so instead use Joe's dash slice move. Whenever the boss is hit, he will move back, then dash forward at a great speed. Jump or somersault over him as he goes past.
If you let the boss get close to you, he will slash at you with one of his swords. As he is doing this, you can throw a shuriken at him them to land a hit. But it is faster to use the dash slice strategy instead. As the boss takes hits, he'll change color until he explodes.