Seiken is a lost and ancient sword style from the days before even Rikudo Sennin. It's so old that, for the most part its secrets have been forgotten. The only people who know of its existence is Haru Chōjin, Ikari Uzumaki, and Nagisa Rinku. Seiken was known for it's great speed, power, and reflexes. Seiken users usually have great chakra control because of the amount of mental training it requires. Legends say that a master can take down half an army of men on their own. All users of this style have to have superhuman speed and strength, either with the help of chakra enhanced strength and speed or with the help of a mutation. The attacks of this style focus on using as few moves as possible to win.