The name comes from a group of nine Mayan deities, the Nine Lords of the Night who from the Underworld of Xibalba ruled over every ninth night forming a calendrical cycle. They were defeated by the Mayan Hero Twins.
In Persona 2: Innocent Sin, they are a (fictitious) advanced race of Maian aliens that guided humanity from ancient times and took control over the starship Xibalba from other Maian aliens through an intergalactic civil war. Their ruins were settled in Sumaru City and the Mayan Civilization was modeled after them. The aliens likely did not exist to begin with and were born from conspiracy theories given life through rumors.
According to Ms. Ideal, the Bolontiku are an advanced race of Maian aliens who guided humanity since ancient times. Supposedly, the aliens dictated their prophecies, the "Oracle of Maia" to Tatsuya Sudou, which if fulfilled, will cause their thoughtforms to manifest physically, at which they will bring destruction to all and evolve those who survived the destruction into "Idealians," a transhuman state where humanity will understand the true meaning of life. Ms. Ideal describes the survivors as having been evolved through facing extinction. Sudou spread the rumor to Akinari Kashihara and Ms. Ideal. Supposedly guided by these aliens, the three collaborated and wrote their prophecies In Lak'ech and kept everything secret to themselves in fear of the prophecies coming to a pass. In actuality, just like the Xibalba, they likely did not exist and are only brought to life by Rumors and the "prophecies" dictated to Sudou are nonsense spread by Nyarlathotep for the sole reason of seeing humanity destroy itself.
Deep in Xibalba, the party runs into an insane Maya Okamura who had now embraced the conspiracy theories written in the In Lak'ech, as these aliens manifest. In the middle of trying to speak Maya Okamura back to her senses, a swarm of these aliens emerge and knock Ms. Ideal unconscious before attacking the party. Each of them have similar weaknesses to of the party's Ultimate Personas, as well as the dark version of their exclusive skills and their dialogue implies that they consider the party as food.
Deal high Wind + Dark damage to all enemies. May cause status ailments. (108% chance)
Trivia[]
The reason why the Bolontiku are portrayed as aliens in Innocent Sin is due to an extraterrestrial origin interpretation on their myth as the lords of the Mayan underworld, with the entrance to Xibalba being a Dark River visible in the Milky Way, something that could be interpreted as having to cross the Milky Way to reach them. In the game, the collective unconsciousness where Nyarlathotep resides in resembles space, but the stars are actually human souls. The rumor that they are Maian aliens who originated from the Pleiades star clusters might also be a wordplay on "Maya," which shares a similar pronunciation with "Maia," as in the Pleiades star or the Greek Maiden where the star got its namesake from.
The party encounters a total of nine Bolontiku aliens, the same as the number of Bolontiku deities in Mayan mythology. However, they end up only fighting five of them, with four of them vanishing directly after the fight.