像青色海洋般的性感偶像，光鲜亮丽的她聚集了所有粉丝们的焦点，直到某一天，一通友人的电话问道：「你的声音和以前是不是不太一样？」，这样的话让女主角反覆思索着，我的声音是怎么样的声音呢？ 当发出这样自问自答的同时，为了别人喜好而同样伪装自己的人也越来越多，但这些人开始感到不安；在演艺界大获成功的偶像被人说，你变得不像自己了，她被困扰着，如同越来越多的人一样思考着，她将找出这个解答，并替大家寻找「杉原杏璃」最初衷的真实人生……

A westerner named Casey, studying Ninjutsu in Japan, is asked by the Sensei to return to New York to protect the legendary Yoroi Bitsu, an armored chest that contains the weapons of the last Koga Ninja.

Fight everyone and trust no one: it's the code of survival practiced by martial-arts master Casey Bowman after his life of domestic bliss is shattered by a savage act of violence. Vowing revenge, the fearless American stealthily tracks the killer from Osaka to Bangkok to Rangoon with the help of a wise and crafty sensei. His only clues: a series of victims whose necks bear the distinctive mark of strangulation by barbed wire. Fighting to avenge as well as to survive, Casey must sharpen his razor-like responses and take his battle skills to the next level, even using deep meditation to fake his own death. His target: the sinister drug lord Goro, who is flooding the streets with deadly meth cooked at his remote jungle factory. To prepare for his ultimate confrontation, Casey must finally become an invisible warrior worthy of the name Ninja. But just when his prey is cornered, an unexpected twist shows Casey that his battle is only beginning: he truly can trust no one.