Tlazolteotl is the Aztec goddess of purification, steam baths, midwives, filth and a patroness of adulterers in Aztec Mythology. In Nahuatl, the word tlazolli can refer to vice and diseases. Thus, Tlazolteotl was a goddess of filth (sin), vice and sexual misdeeds. However, she was a purification goddess as well, who forgave the sins and disease of those caused by misdeeds, particurlarly sexual misdeeds. Her dual nature is seen in her epithets; Tlaelquani ('she who eats filth [sin]') and Tlazolmiquiztli ('the death caused by lust') and Ixcuina or Ixcuinan ('she of two faces'). Under the designation of Ixcuinan she was thought to be plural in number and four sisters of different ages by the names; Tiacapan (the first born), Teicu (the younger sister), Tlaco (the middle sister) and Xocotzin (the youngest sister).
Her son was Centeotl and she was also known as Toci. She presides over the 13th trecena of the sacred 260-day year. Another son is Yum-Kax, the Mayan maize god.
"The Aztec goddess of filth. She is also the goddess of sexual deeds, as well as a goddess of purification. She is also known as Tlaelquani ("she who eats filth"), befitting her nature as a goddess of atonement."
—Shin Megami Tensei: Strange Journey compendium
Shin Megami Tensei IV
Tlazolteotl is faced in the Challenge QuestThe Only Food Source, where the client wishes Flynn to retrieve a stash of corn she guards, yet refuses to eat, instead targeting humans as her food. She is found in Blasted Tokyo's Ikebukuro Underground Shelter where she has placed a Domain on the bottom floor. She asks what business Flynn has with her and confirms the back room is filled with corn. She doesn't allow him to pass as giving it to humans is forbidden, stating he'll have to go through her, accepting the challenge when confronted.
She is indifferent to her defeat, saying she is tired of eating corpses and unlocks the door to the corn before disappearing. Her purpose is revealed by a Dis to be eating corpses, cleaning impurities and cleansing the soul on the orders of the gods who sought man's annihilation. As a goddess of harvest before she became a goddess of filth and purification, she wanted to return the corn the humans worked hard to grow, so she had kept it to ensure that humans would eventually reclaim it at her defeat, defying the very purpose she had been given to annihilate them.