Within the Takeda-ryu Maroto-ha school, the art of Shuriken-jutsu, because of its dangerosity, is reserved only to an elite, 5th dan at least in Aïki-Jujutsu or Iaïdo.
Indeed, one must have a great well balanced mind to be able to master this martial art which perfectly completed the Takeda-ryu Iaido (swordsmanship).
Actually, this art consists in throwing "shaken", weapons made of wrought iron spikes.
Training requires a lot of discipline and stability. That kind of weapons becomes truly efficient only when the posture of the body and the holding technique are accurate.
It’s an exercise in accuracy which requires great skill, perseverance, calmness and concentration.
There is no rank for that discipline within the school Takeda Ryu Maroto-ha. It is a discipline considered as supplementary to a main discipline (Aiki-jujutsu or Iaido).
Those weapons are not to be put in all hands, especially not to children ones.
Our art of Japanese sword is not taught before age of 14. In addition, a waiver must be signed by the parents of minors and by adults practitioners as well. The use of sharpended swords is absolutly prohibited.
It's actually only Iai-to, which are only replicas of real sharpened Katana, rightly regarded as decorative or ornamental swords.
World Takeda-Ryu Marotokan Federation - International Official Site