Cthulhu (ク・リト Ku Rito, "K'lt") is a Tribe in Z/X -Zillions of enemy X-. They are the first major Tribe (and the second after True Dragon) to be colorless, although colored Cthulhu cards also exist in small quantity.
Z/X Encyclopedia Entry
A newly discovered Tribe.
They are lifeforms of a different notion from those evolved from humans, or perhaps beings created by the future humans, the Z/X. Even though there are some individual differences, they possess the appearance of human girls with new parts such as tentacles and eyes attached to them, and collectively known as "Cthulhu". Nevertheless, they remained as an "abnormalities" for present-day human, and there are some people that lumped them together with the existing Z/X.
Their origin is often listed as the "Othersea", a place said to be exist in faraway space and connected to the depths of ocean in the world where we lived. It seems that they had manifested themselves before us occasionally in the past, but their existence are only recorded in minor folklore and fiction. Because their native names are all difficult to pronounce, the point of differences with the one recorded in literature was caused by the lack of credibility.
While they held a great interest in pleasure, each one of them also hid an enormous power. For that reason, getting on the wrong side of them is capable of causing not just individual death, but may even invite the destruction of a species. In the distant past, they also left some kind of problem sources among the gods (Dynamis). Enlil, who inherited the dim memories of ancient times, bear an extraordinary hatred against the Cthulhu.
They manifest themselves using other lifeforms on the earth—mainly using human body as their medium, and their appearance are often influenced by the original human.
In the Z/X -Zillions of enemy X- TCG, the Cthulhu are first teased in Set 27 through various pieces of flavor text and the Shift card for Yutaka Tenryu before officially introduced in Set 28.
The names of the individual Chtulhu are taken directly from the various entities, races, and beings in the Cthulhu Mythos that serves as their basis. In addition, their written Japanese names are also modified from the original names, mostly shortened or scrambled to gives the sense of "difference" as stated in their Z/X Encyclopedia entry.
Similar to the Dingir and Waker, Cthulhu and its cards also comes with their specific card frame for their main deck cards. They have their name, or related names for non-Z/X cards, printed horizontally in heavily stylized and mirrored Latin characters on the right side of the card not unlike the Dingir character.
As a colorless Tribe, their cards has a wide range of abilities with the major focus on fully utilizing their Z/X Overboost and Shift cards as well as Token creation.