Master Nawa Yumio (pictured on the right with ninjutsu teacher, Hatsumi Masaaki. Mr. Hatsumi was apparently an early student of Nawa Sensei prior to training with Takamatsu Toshitsugu) is a martial artist, historian, writer and advisor to the Japanese Government's NHK T.V. Network, considered to be a leading authority on ninpo. In addition to ninpo, Nawa sensei is also talented in the arts of Masaki ryu manrikigusari, Masaki ryu kusarigama, Edo Machikata jutte and Torinawa Atsukaiyo (jutte and tying cord) among others. Mr. Nawa currently teaches at the Masakikai in central Tokyo.
It is commonly accepted that the Manrikigusari (ten thousand power chain, aka: kusari fundo) was developed by a well known swordsman of his day, who was the head sentry at the main gate of Edo-jo (Tokyo castle). It was during this time that this samurai (named Masaki Tarodayu Toshimitsu) became concerned that, if an intruder were to try to enter the castle, a conflict would result in the spilling of blood on castle grounds. The drawing of a sword inside of a castle was forbidden, and the result of this limitation can be seen in Masaki's catalog of techniques using a short weighted chain, effective and still practiced by a few dedicated students today.