The Boundless Sigbin emerged when a singular Sigbin discovered an ancient artifact buried beneath a Filipino mountain that granted it the ability to transcend physical limitations, allowing it to traverse between different cryptid domains. As it journeyed across realms, it collected blood not to consume but to preserve the genetic memory of cryptid species, becoming the living archive of cryptozoological knowledge that connects all cryptid manifestations across time and space.

The Boundless Sigbin can become completely invisible except for its shadow, allowing it to observe cryptid activities undetected. Its whip-like tail glows with ethereal energy when creating portals between cryptid domains, enabling instantaneous travel across vast distances. Specialized translucent organs within its body store and preserve blood samples from every cryptid it encounters, maintaining their genetic memory and unique properties. Most remarkably, it can temporarily manifest characteristics of any cryptid whose blood it has collected, serving as a living demonstration of cryptid diversity.

The Boundless Sigbin serves as the living archive of cryptid genetic memory, preserving and connecting diverse cryptozoological traditions through its blood collection and ensuring the continuity of knowledge across all cryptid species regardless of their geographical or dimensional isolation.