Mishaguji (ミシャグジ?) also known as Mishaguji-sama (ミシャグジさま?) is a demon in the series.
Mishaguji was a native god worshiped in the ancient Shinto region of Japan before the Yamato took control, at which point the worship of it became a taboo. Mishaguji was the god of sexual intercourse and if he was left an offering, then sex would become better. It is said that Mishaguji's incarnation on Earth had a very phallic shape, possibly similar to an earthworm, and he would take shelter under rocks or stones. Once Yamato took control however, Mishaguji became seen as a god that only the undesirable and unfaithful would worship.
"Origin: Japan. A malevolent god that is enshrined at Suwa. Since he is also considered Tatari-gami, careful worship is required. Some theories say that when Take-Minakata escaped Suwa to get away from Take-Mikazuchi, he became a native there and became Mishaguji"
—Shin Megami Tensei A-Mode DDS Dictionary
Shin Megami Tensei IMAGINE
Mishaguji acts as one of the five demons that controls the Pentalpha system. Players can align with him to fight against mobs representing the other demons within the system. Those fighting against him will face waves of demons belonging to the Wilder, Raptor and Evil Demon races.
By acquiring enough power for him, players can obtain the ability to fuse him in a special fusion of Take-Minakata and Sarutahiko.
Shin Megami Tensei IV
Mishaguji is one of the demons summoned by Hiro Jingu in the third round of the "Hunter Tournament Finals" Challenge Quest. He later appears as a regular encounter in Ginza. Mishaguji can teach Flynn the Acid Breath, Mazionga, Pulinpa and Madness Needle skills through his Demon Whisper.
Shin Megami Tensei IV Apocalypse
Mishaguji can be found throughout Ginza. It can teach the Rakunda, Mazionga and Madness Needle skills through its Demon Whisper. Mishaguji benefits from learning Electricity, Darkness, ailment and support skills.
Devil Summoner: Soul Hackers
"A native god worshiped in the Shinano region before the Yamato power took control. Said to be a god born from the ancient belief that rocks and stones housed divine spirits."
—Devil Summoner: Soul Hackers 3DS compendium
Devil Summoner: Raidou Kuzunoha vs. The Soulless Army
User may follow-up user's row's attacks, for 3 turns.
A heavy Bash attack, lowers target's defense for that turn. (1 enemy)
[Navi] Gather safely from Power Spots.
A heavy Almighty attack, with medium chance of knockdown. (All enemies)
Greatly raise natural recovery speed from status ailments and Binds.
Remove stat buffs. (All enemies)
A heavy Cut attack. (All enemies)
Mishaguji in Devil Summoner: Soul Hackers
Mishaguji-sama as he appears in Shin Megami Tensei IMAGINE
Mishaguji-sama as he appears in Card Summoner
Mishaguji as he appears in Persona 5 Royal
According to the Japanese scholar Yanagita Kunio, Mishaguji used to be a guardian deity for travelers, worshiped under the guise of a phallic stone pillar; at the same time, due to religious syncretism, one of his other forms was that of a white Japanese rat snake.
It is thus possible that Mishaguji's design was inspired by a combination between the snake  and pillar  forms.