Vaishravana
Vaishravana (Skt. Vaiśravaṇa; Tib. Namtösé; Wyl. Tib. rnam thos sras; Eng. 'Son of He who has Heard Many Things') — one of the Four Great Kings. Guardian King of the North and leader of the yakshas.
Wearing golden armour, Vaishravana protected the gods from the asuras (demi-gods).
Vaishravana now occupies the highest position among the Four Guardian Kings and specifically protects Shakyamuni’s Vinaya teachings, protecting those who practise shila (self-discipline).
Because his breath is harmful he keeps his mouth tightly closed. He confers spiritual and material wealth on practitioners of the Dharma, symbolized by the jewel-producing mongoose in his left hand.
For more details see Crystal Mirror, volume VI, Dharma Publishing 1984