There are those in the Bujinkan who do not follow Kokoro, instead they follow a more violent path while living on the dark side of the force.

  The Bujinkan is perhaps the only Martial Arts in the world that encourages harmony among both Light and Dark. The darkside is there for us to acknowledge but not get too close, the light side is the path that will help us understand our true nature.

  I think Sensei would like students to be strong enough to transcend Light or dark and not being caught up in it all. The Bujinkan was once compared to a swamp, only the strong and pure of heart will be able to survive and pull themselves up.

  One thing any good teacher will be able to do when evaluating students is to see if they have an affiliation with the darkside of the force, it's ok if they do as long as its manageable, too much may mean they are not suited to study Bujinkan for obvious reasons.

  Students prone to violence should not be taught Hatsumi Sensei's Budo this is without question.