The easiest way to get scrolls is to fill your inventory with bamboo traps. Simply line them up one after another in the path of an enemy so that he will hit the first one and bounce to the next one until he has hit all eight traps. If done correctly, each time the enemy bounces off a trap he will drop one of the following: money, ninja gear ingredients, or sometimes a scroll. Also, you can sell the eight trap kills you just got at the shop for money.
Kill types
The ten types of kills you can get are as follows: Sword Kill, Trap Kill, Poison Kill, Water Kill, Explosive Kill, Spike Kill, Tiger-Trap Kill, Fall Kill, Surprise Kill, and Joke Kill.