Imagawa clan
The founder of Sekiguchi ryu was Sekiguchi Yarokuemon Ujimune, also known as Sekiguchi Jushin. Jushin was part of the Seiwa Genji Imagawa clan of the Sengoku period. When the once powerful Imagawa clan fell to the conquests of Oda Nobunaga, Jushin decided to dedicate his life to martial arts training. He left the castle for the Atago Mountains where he underwent intense physical and spiritual training. The result of that training became known as Sekiguchi ShinShin Ryū, and rumors of the wanderer and of his art rang throughout the country.