Yamamoto writes a bit on his site about his inspiration, his materials, and his method:
The mainspring of my work is derived from the death of my sister from brain cancer ... Since then, I have had the dilemma, in grief and surprise, of thinking about what I had and lost. I started making art works that reflected such feelings and continue it as if I were writing a diary. Many of my works take the form of labyrinths with complicated patterns, ruined and abandoned staircases or too narrow life-size tunnels, and all these works are made with salt. Salt seems to possess a close relation with human life beyond time and space. Moreover, especially in Japan, it is indispensable in the death culture. After my sister's death, what I began to do in order to accept this reality was examine how death was dealt with in the present social realm. ... Drawing a labyrinth with salt is like following a trace of my memory. Memories seem to change and vanish as time goes by.