When to Switch
One can become a ninja at Lv100, by taking the quest 'Ganaji Professions' from Suigetsu in Minaula City. Some people recommend that you wait until Lv140 to switch to ninja to get the skill "Dance of Clones", but not having this skill for 40 levels is not a big deal. The most important thing however is to make sure you have good equipment and plenty of spina at Lv100. This is the most important thing you should focus on before switching your class to ninja. Without proper equipment and consumables, one may not be able to make clones, which completely defeats the purpose of switching one's class to ninja. Ninjas need plenty of vaccines, antidotes, and eye drops to avoid dying quickly. Please note that after switching your class to any special class, you will lose all of your previous skills and can only switch to other special classes.