Ikkō-shū (一向宗) or "single-minded school"[1] is usually viewed as a small, militant offshoot from Jōdo Shinshū Buddhism, though the name has a complex history.
Originally, Ikkō-shū was an "obscure band of Pure Land proponents" founded by Ikkō Shunjō in the fifteenth century.
The Amida pietist movement, and in particular the Jōdo Shinshū, also provided a liberation theology (or ideology) for a wave of uprisings against the feudal system in late-fifteenth and sixteenth century Japan which are known as the Ikkō-ikki revolts.
As a consequence of the Ikkō-ikki revolts and the growing power of the Jōdo Shinshū, the sect's fortress-temples Ishiyama Hongan-ji and Nagashima (built at the end of the 15th century) were eventually destroyed by Oda Nobunaga's armies.
Following the destruction of Nagashima, Nobunaga ordered his men to search all of Echizen Province and kill every last man and woman of the so-called Ikkō sect.