In the beginning of the game, you start with only the Throwing Star for a weapon. As you successfully complete bonus stages, a monk will offer you more weapons to use against your enemies.
- Throwing Star
- Crescent Blade
- Ninja-kun does not have to earn this weapon, but it is only accessible when he is swimming. It has a very short range (about the size of Ninja-kun's body), but it is very fast and can be swung rapidly.
Normally, Ninja-kun can only throw up to two of each throwing weapon on to the screen at one time. However, if he successfully completes a bonus stage while still in possession of a fireball, he will be able to throw up to three of each weapon on the screen at one time.
When Ninja-kun kills one of the six basic enemies, it leaves a scroll behind. They are worth 100 points more than the number displayed when you collect them, plus an additional 100 points more if you clear the stage. The scrolls that you collect appear in the lower left hand corner of the screen. You can collect a maximum of 12 scrolls. (In the home conversions, this limitation is removed, and the number of scrolls is shown numerically at the top of the screen.)
Scrolls appear wherever an enemy is defeated. If you remain standing where an enemy was killed, the scroll will not appear until you move from that location. Scrolls remain on the screen for six seconds before they disappear if they are not collected. However, only one scroll can appear on the screen at one time. If you kill another scroll-producing enemy before the first scroll is collected, the first scroll will disappear immediately.
When you collect a scroll, there is a random chance that the face of a princess or a monk will appear. If a monk's face appears, all of your scrolls are lost. If a princess appears, the number of scrolls in your possession will double, up to a maximum of 12. Therefore, if you have 7 or more scrolls, you will only ever receive 12 scrolls. If you have 0 scrolls when a princess appears, you will still have no scrolls.