Ninja - The Assassin of Darkness is already available in Black Desert Online SEA. Have you tried it?
Ninja is an assassin type class that uses swordsmanship, bodily skills and Ninjutsu. His combat style is based on the character’s great mobility. Ninja also uses a variety of crowd controlling techniques to fiercely attack the enemies. You can choose a Shuriken that magnifies your AP as a sub-weapon, or a Kunai that complements your DP.
Ninja isn't the easiest class to control, but once you get used to, it you'll begin to feel the amazing power of this class.