Turdak is a Tibetan lesser deity associated with illness and death. He is a servant of Yama and is depicted as a humanoid skeleton. While Turdak can bring illness and plague upon mankind, he also has the power to cure illness, or expel illness-causing demons if a dance is performed for him.
Turdak is also seen in Hindu mythology, where he is again the servant of Yama, judge of the dead. Turdak's role has changed, and he is considered an executioner of judged souls. After Yama has pulled a soul from a corpse and sentenced it to Hell, it is Turdak's job to haul that soul to the proper level of Hell.
"A skull that serves his relative Yama, lord of the dead. He is viewed as the embodiment of disease, and often depicted as a skeleton. Turdak can bring disease and send people to their deaths, but he also has the power to cure disease by dancing. He is often described as a pair of beings, one that brings disease and one that cure it."
—Shin Megami Tensei IMAGINE Compendium
Turdak can be contracted in the bronze level of Ichigaya's Kagurazaka Zhu Que Caverns. He appears as a field boss in Ichigaya, a nightmare mob in the basement levels of Old Ichigaya Camp, and a regular mob in Ikebukuro's Zoushigiya Cemetary.
"A Hindu executioner of judged souls, under the command of Yama, the god of death. When Yama passes his judgement, it is Turdak's task to haul the soul to the proper hell."
—Devil Summoner devil chart
Turdak appears during an ambush set for Raidou in the basement of the Daidouji Residence while investigating the rumors about the basement. After reading Kaya Daidouji's diary in the cell found within the caves, when Raidou tries to leave he will find his way blocked by the demons, with Gashadokuro appearing behind him. Gashadokuro states that since Raidou read the diary, he must be killed. The Turdak demons will then join Gashadokuro during the battle. The two Turdaks will attempt to gang up on Raidou during the encounter, and Gashadokuro will summon more as they are defeated.
Ichimokuren will also summon two Turdaks as support while battling Raidou, and will do so in waves. He will close his eye and become impervious to damage until the two Turdaks are defeated, then go on the attack. He will then again summon two Turdaks before defending again. When low on health, Ichimokuren will again summon two Turdaks, but remain attacking during this phase.
Turdak can only be fused after getting the Scarlet Brace Key Item from completing the request, Time For a Warm-Up. The request involves fighting Elizabeth wielding Turdak as her Persona, and is available after reaching Group Date Cafe Stop 4.