Saigenzai

is category of hypnotic drug that appears in The Wolf that Howled at the Sun. Depending on how it's prepared, saigenzai can be used to erase memories or control others. It is popular in the Howling Wolf Village as a narcotic, used by former shinobi to cope with their uneventful lives. Members of the Kodon clan are able to prepare a special version of saigenzai called Kotarou, which can be used to treat severe illnesses.