Old Ones (先人, Senjin)? are a species that appear in Devil Summoner 2: Raidou Kuzunoha vs. King Abaddon.
The term "Old One" is used to refer to a god or deity, and have been used in fantasy horror and science fiction, quite commonly in H.P. Lovecraft's fiction in various context.
The Tento Lords show a bit of a God Complex and hate being shown disrespect by the humans they despise and look down upon. They look upon humanity with racist views, though some do enjoy human women.
Before the Game
According to the Old Ones, they were the first beings to walk the earth, but a great disaster happened one day that nearly wiped the species out. In order to survive they lived on a ship. However, they traveled for so long that they eventually began to deform and mutate. Becoming what they and humans consider to be hideous beings and must wear an insect like mask so that they will not show their true face. Eventually they found land and traveled to a small corner of the Tsukigata village where they finally decided to live after their long travel.
The humans of the village however ostracized them for their hideous appearance and forced them from the village. They fled and hid under the village to survive. From here the group split into two, those who would become known as Lord Tento who would hate the village for how they were treated and play pranks and tricks on them. They would also take control of the village through the creation of the Luck Locust and Soldier Bugs which only the Old Ones could make. In return for the insects Lord Tento demanded they sacrifice the Tsukigata women in order to repopulate their own race, transforming the women into something else over time.
The other group known as Mushibito would go into hiding and would not persecute the village for what they did. Instead they follow the words of Lord Bellzeboo who brings prophecy to them. One would instead write the poem about Ma which would eventually be retold by Lord Tento and learned by the villagers despite not knowing it's meaning. They are also not hostile like the Lord Tento ones are and remember the past. Unlike the Lord Tentos who choose only to remember the hate.
During Raidou Kuzunoha vs. King Abaddon
Raidou meets and battles the Tento Lords during Chapter, where they learn the truth behind the Marriage Ritual and Dahn's actions. Dahn wishes to become King Abaddon so that the village will no longer depend on them. An angered Tento Lord unleashes the Soldier Bug Tentomaru after being hit and shown disrespect by Dahn and Raidou.
- It is implied that the Old One's are the iron forging civilization that predates the Japanese being able to forge iron. Which is mentioned by the NPC Yanagita and characters during the game.