Actually these claims do have substantial backing and I'm sorry they are not just "sounds in the wind." As I stated before they are backed by Japanese historians, the Iga-Ueno Ninjutsu museum, and also the government. It is also well-known among Japanese martial arts Sensei's here that if you want to train in Ninjutsu(authentic/real) there are only two people to go to............Jinichi Kawakami and Yasushi Kiyomoto. Most recently they were featured in "ANA's" magazine "Wingspan." For those of you that don't know "ANA" stands for "All Nippon Airways" and is a major Japanese airline company. "Wingspan" is a magazine given out on each flight in Japan. Quoting from the magazine, "from youth he dedicated himself to ninja ways, with a meatless diet and intense physical training." "Kawakami is deemed 21st head of the Ban family of the Koka ninja school." "True ninja passed their final secrets to but one individual. Even in ninja families, only one son inherited the full ninja mantle (referring to Kawakami)." This is published in English. It is the September, 2007 issue of Wingspan for ANA. There are several publications mentionining Jinichi Kawakami and Yasushi Kiyomoto. Most are in Japanese. I have trained under Kiyomoto-Sensei for over a year now.........about 99% of the time it's been one-on-one. He has trained in Ninjutsu for practicly his whole life. His body is hardened from training and he can move in ways that most people can't. I trained with quite a few well-respected martial artists in America from various disciplines........nothing has come close to what I have seen in Japan. Kiyomoto-Sensei is well-versed in the military arts and definitely knows his stuff. The class can be extremely rough............you will get hit, you will get bruises, and yes, you might bleed but you will also learn things that you can't learn anywhere else on earth.