"As a Defender of Law, Koumokuten is considered one of the Four Heavenly Kings featured in Buddhism. He holds a three-bladed vajra and has been assigned by Lord Sakra with protecting the western domains of Mount Neru. He has strong ties with the Naga, and is sometimes depicted as being their king. He is said to be omniscient, a power he uses to find evil deeds being committed all around the world and redirect these sinners towards the path of righteousness."
—Shin Megami Tensei IMAGINE Compendium
Koumokuten can appear alongside the other kings in Ichigaya Camp's gold-level instance by defeating the Pisaca mini-boss on the basement floors.
Shin Megami Tensei IV
Koumokuten is faced in the Challenge QuestTokyo Cosmo. He is found in the Nakano area of the Shinjuku Region. He appears alongside the other three once all four have been defeated to be fought as a group. Koumokuten mentions after the Four's final defeat that Flynn is the only one to defeat them without the Orb of the Four Gates breaking.
Persona 3
"Virupaksha, protector of the West, is one of the four Heavenly Kings of Buddhist origin."
—Persona 3 Compendium
Devil Survivor
Koumokuten (named Koumoku due to character space limit) is one of the four Devas that protect the barrier between the demon and human worlds. On every ending save for Yuzu's, in order to gain access to the demon world (and thus, Babel) the player's party needs to dismantle the barrier that the Devas protect. After Bishamon's defeat, Koumoku challenges the player's party with Zouchou, planning to make up their lack of power with numbers.
Koumoku and Zouchou are unlocked for fusion after the player defeats them.
Devil Survivor 2
"Koumokuten, or Virupaksha, is one of the Four Heavenly Kings in Buddhist lore. He dwells halfway up Mt. Meru in the center of the world and protects the West under the command of Sakra. He keeps a close watch on the world with his sharp gaze and enlightens people with his speeches. He is commonly depicted wearing armor, with an trident in hand and an angry expression on his face."
