Serpo

Being a wholly male species, the Serpo have no natural means of reproduction and lean on cloning instead. Yet evolution stalls among identical beings, and once they grasped how this had frozen their development, they began seizing people from Earth to strip their reproductive organs, which they nickname bananas. Their fascination later turned to spiritual abilities, gifts they aim to absorb to push their species ahead, since such powers regularly eclipse even their formidable technology.

In public the Serpo hide inside grey-skinned, roughly male humanoid disguises wearing matching outfits: white collared shirts tucked into grey slacks, leather belts, brown shoes, and thin lips pulled into disturbingly broad grins. Stripped of the costume, their real heads are angular and slug-like with bulky lips and wide teeth, their dark-patterned bodies sharply cut at the shoulders. Each hand bears two thumbs and two fingers, their feet split at the tips, and their crystalline headlight eyes glow in shades that shift by individual, ranging from cyan and red through green, purple, pink, or yellow. They treat captured humans with oblivious brutality, certain they arrive in peace, while favoring female targets and loathing anyone who fights back. They are just as cold to hired help, viewing subordinates as cheap and swappable, as when they slashed the Dover Demon's pay and shot him with a mutagen despite his protests.

Decades back, with backing from aliens left over from the Roswell Incident, the U.S. military dispatched a dozen humans to Planet Serpo for a research exchange. Two of them perished on that world, eight made it home only to die from the brutal ultraviolet radiation they had absorbed, and the last two chose to stay behind, their fates never revealed. In the present the aliens grab Momo Ayase at Nagi Hospital to harvest her organs, but overstimulating her brain accidentally awakens her psychic powers, and she wrecks their craft. Drawn to the abilities Okarun displayed while possessed by Turbo Granny, they hunt him down, bringing the Dover Demon, plus Nessie to serve as muscle, yet Aira's interference and Momo's return swing the clash. Down to a single survivor, that Serpo fuses with both hirelings into the Serpo Dover Demon Nessie, which Okarun eventually destroys.

Setbacks pile up afterward. Kur invaders storm a Serpo base, butcher the clones, and make off with their data and equipment, which lets them hijack disguised Serpo planted at the Moe Moe Kikoho where Momo waits tables. A broken Serpo sides with Momo to smash and reset the hacked clones, and once the dust settles the survivors crack open a captured exosuit head, learn the planet-eating invaders hail from beyond the galaxy, christen them Kur, and alert other species while fretting over Saint-Germain's involvement. Afraid he might grab the shrunken Momo, they fling the Typhoon Human at her Shimane-bound plane, then decide to gather an army for close-quarters fighting. They contract Red Baron next to their agent Reptilian to capture or kill her, and at last bring Mr. Dris into a small clone force to corner the powerless Momo and Okarun outside a museum, where Okarun parries Mr. Dris with the Oni Club.

Rather than separate personalities, the Serpo mostly turn up as interchangeable clones, a product of their identical, data-built manufacture. The clearest exception is the broken Serpo, tied to the Rokuro Serpo, who lives through a Kur raid and reluctantly joins Momo to reset the hijacked clones and recover stolen data. Whenever a clone's birth data is rewritten, the altered This Man form results, complete with its own hand-clapping way of triggering psychokinesis. Outside their own kind, the Serpo rely heavily on disposable hires such as the Dover Demon, Nessie, the Typhoon Human, Reptilian, and Mr. Dris, along with the assassin Red Baron.