Titan.Darkestknight said:
Someone said it means to Sacrifice, or Wooden Man, so I doubt it's Silence or Sleep.
Japanese
身替の術:壱 忍Lv88
※詠唱するためには、忍び道具「木人」が必要です。
身替 is apparently migawari, although I'd write migawari 身代り. 身替 is either a very formal/archaic way to write it, or something else. It means "substitute" or "scapegoat." (The rest of the spell name in japanese is inconsequential --> migawari no jutsu ichi)
It does indeed use the tool mokujin 「木人」, which literally translates by the kanji into "wooden man."
Before I read the POL notes in Japanese, I was really hoping for mokujin to be written this way: 黙塵, which could be read as "silence dust" lol.