The reign of the Steel Chrysanthemum was one of the most heinous time periods of Rokugan’s history, and the excesses of the Emperor were such that he drove his own mother and brother - along with many other men and women of honor - to join together in secret to oppose him. The terrible crime of regicide, an act normally regarded as absolute blasphemy and among the greatest sins comprehensible in the Empire of Rokugan, became the only viable option.
Otomo Nazeru created the Technique of this group, but stopped teaching it to others the moment his older brother died. Nonetheless, it is possible the Technique might be preserved into later eras, or even recreated by a different group rebelling against a tyrant. (Timelines such as a Thousand Years of Darkness would be good settings for this Technique.)