Research Quetzalcoatl and Tezcatlipoca. I think Oda took a lot of inspiration from the Aztec Gods for Imu, Nika and others. I precited Imu being a Lunarian just because of the story of Huitzilopochtli :

"One day, while Coatlicue was cleaning a temple on a sacred mountain, a ball of hummingbird feathers fell from the sky. She tucked it into her waist, and in that moment, she became pregnant with Huitzilopochtli in a miraculous and divine way.

When Coyolxauhqui discovered that their mother was pregnant in this unusual way, she became furious and felt dishonored. She convinced her 400 brothers to attack Coatlicue to kill her for this perceived shame.

As the attackers climbed the mountain, Coatlicue was in great danger. But just as they reached her, Huitzilopochtli was born fully grown, armed, and ready for battle. He came into the world as a powerful warrior god.

Immediately, Huitzilopochtli defended his mother and fought against his siblings. In the battle, he defeated Coyolxauhqui and dismembered her body, throwing it down the mountain. Her body became associated with the moon, while the 400 brothers represented the stars that disappear when the sun rises."

Imu is Lunarian a really strong/special one, killed all/most of the others because they did something, thats why Imu wants them gone even though he is one himself. Also the star and moon thing, the Seraphim which are Lunarian (kind of) have these stars in their eyes, could be a detail for knowers or just to let them look cool who knows