The requirement of job change is a Novice with Job Lv10.
1. Proceed to the Ninja Guild at Amatsu 147 136. Try to go into the invisible path (Hint:Look for the Japanese character on the wall) at que_ng 21 151. Find the Cougar Guy NPC and talk to him. You need to take the task of delivering the letter to Wildcat.
2. Proceed to Einbroch 184 194 to talk to Suspicious Man (to reach this NPC, firstly talk to Kincaid at Einbroch 176 170, pay a fee and take a tour) and he will help you to look for Wildcat. However, player needs to finish the task given by him. Task: Gather Cyfar x 5, Phracon x 1.
3. Once you have completed the task given by him,you will come to know that the Suspicious Man is the one who wrote the letter given out by Cougar Guy. He will tell you that Wildcat is the nickname given by Guy. He is the rival of Guy who is known as Red Leopard Joe.
4. After receiving the letter from Guy, Joe will write a reply to him. He will send you to Amatsu by warp portal.
5. Find Cougar Guy again, he will require you to deliver the letter to him and get back the reply letter. He also wants you to help him to create weapon by gathering the materials for him. The ingredients are the same: Cyfar x 5 and Phracon x 1.
6. Talk to Guy again you will be able to perform job upgrade after gathering the correct materials, you will receive Asura x 1.
Some Details about Ninja job:
i. Ninja can reset skill if Base Level is 40 or below
ii. Ninja's weapon can be refined by Whitesmith
iii. Ninja cannot be adopted