The character known as Boogiepop in the anime Boogiepop Phantom is not the same entity as the one from the original light novels, though it shares a name and a similar purpose. This being is a Phantom, a unique type of lifeform born from an intense surge of electromagnetic energy. Specifically, it was created from the Manticore's fear of the original Boogiepop at the moment of its death, and from the data transmitted when the alien Echoes transformed into a pillar of light. Because it was born from the Manticore's perception, it does not know Boogiepop's true face; instead, it manifests using the appearance of a girl named Minako Yurihara, who was the form the Manticore had taken. It is a semi-corporeal being, an electromagnetic lifeform that can phase through objects and appear or disappear at will anywhere within the distorted magnetic field covering the city, a field that will only last for about a year.

The personality of this Boogiepop is one of profound and uncanny calm, even more so than the original. It shows very few signs of human emotion, acting with a perpetual, incongruous serenity that makes it seem detached from the world around it. It is not hostile to ordinary humans and never intentionally harms them. However, it has no inherent attachment to its own existence and does not intend to persist beyond the natural dispersion of the electromagnetic field that sustains it. Its demeanor can be seen as indifferent, even cruel, as it once told a character she was not worth the effort of being taken by it.

The central motivation and role of Boogiepop Phantom is to safeguard a group of young people who have been granted extraordinary powers, known as MPLS (Evolved Humans). Unlike the original Boogiepop, which often eliminates such threats, this Phantom seeks to preserve them. Its method is to seek out these individuals and seal them away, trapping them in a state of cold sleep inside a cocoon hidden beneath the town. The Phantom does this not out of malice, but out of a desire to protect them until such a time when the rest of humanity has evolved enough to coexist with them. In this way, it acts as a keeper for the future, pausing the present for the sake of tomorrow.

Key relationships in the story are defined by this mission. Boogiepop Phantom shows no hostility toward the original Boogiepop and is even seen cooperating with it, working together to corner a common enemy and leading the original to the sleeping MPLS. It also interacts with the vigilante Nagi Kirima, who investigates the supernatural events plaguing the city. While it does not attack her, it will take action to protect its own survival, such as disabling her electronic equipment. The Phantom’s development is less about emotional growth and more about the completion of its function; it is a temporary mechanism with a single, self-contained purpose, and it pursues that purpose without deviation until its time runs out.

The most notable abilities of this entity stem from its nature as an electromagnetic lifeform. Its semi-intangible body allows it to phase through solid objects and travel freely across the city's electromagnetic field, appearing and disappearing at will. For combat, it wields an ultra-sharp microfilament wire, much like the original Boogiepop, using it as a devastating cutting weapon. However, because it is not a physical creature, it does not need to use the wire for mobility in the same way a human would. The Phantom’s primary power, though, is its ability to locate evolved humans and place them into a stasis cocoon, a power that defines its entire reason for being.