How many chapters ninja gaiden 2

There are around 20 levels in Ninja Gaiden 2, each level increasing in difficulty.

Also here are some secrets too defeating the 3 greater feinds

With Alexi, your best bet is the Dragon sword because it is more agile and you can use the Reverse Wind Technique.

Volf is really easy to beat. He just charges at you.

Zendonious takes awhile. Your best bet is the Eclipse Scythe. Use the dash and Y to hit him. Also attack him when he raises fire from the ground.