魔
マ
witch, demon, evil spirit
JLPT1 G7 S21 F1514
As per 麻# (rub and scrape) + 鬼 ghost; demon → *demon* that figuratively rubs a person's senses into numbness. There is a strong likelihood that 魔 was devised to transliterate the first syllable of the Sanskrit Mara, referring to one of the gods in the Indian pantheon.
[Full Kanji Etymology List]