Gouki and Genki
The Nio are the guardians of the Buddha.
Agyō 阿形 (mouth open) and Ungyō 吽形 (mouth closed)
ah and un
Death Zen, encouraging people to meditate on and in the forms of buddhist iconagraphy.
He stressed that through performing zazen while in the posture of the Nio, and maintaining an ever present sense of death energy, once may maintian enlightenment despite circumstances.