One of the three races of legendary monster in the Xyniverse, Squi is an Armageddon Squid. Since on occasions, saying things like "giant, mutant, killer, snail of Amaranis" isn't very convenient, the Apocalypse Serpents, Armageddon Squids and Amaranis Snails are often shortened to Aserpent, Asquid or Asnail. Squi has two roles in the Xyniverse, but her main one is that of the young leader of the underwater syndicate, Squid Force.

Often getting tangled in her own tentacles, Squi also happens to be a "Command Class" Asquid. Normally, Asquids can evolve, adapt and assimilate using their tentacles as tools and extensions, but every while in a blue moon, a Command Class Asquid is born that has the ability to control other Asquids and use special powers reminiscent of magic.

For a large part of the Xynthica Saga, Squi and Xyni play a rather comical game of cat and mouse, with Squi appearing randomly throughout Xyni's adventures to harass her. Of course, despite being female and straight, assaulting an innocent little girl with a flurry of tentacles tends to draw unwanted and highly disapproved attention from even the most lazy of innocent bystanders, so Squi's "secret" missions frequently fail. The reason why Squi attacks Xyni originally, is because she is friends with Kibsy, and since the Armageddon Squids and Amaranis Snails are natural mortal enemies, she saw it fit to make it her goal in life to traumatize both of them. Later in the story, Squi is promoted to the full on overlord of Squid Force, but by this point, she becomes friends with Xyni, and joins her as one of her three monster companions along with Rally and Kibsy. Squi also has the ability to turn into a human form when she gets older, but the specifics are unknown.