Pipi faithfully accompanies the divine being Kaguya within a limbo dimension bridging the moon and Earth. Together, they undertake missions to Earth, countering human sorrows that threaten to destabilize the moon's orbit. During their first mission, Pipi observes Tanaka's rejection by Ikuko and helps prevent his impulsive suicide attempt. Later, Pipi retrieves Tanaka when he flees in fury after witnessing Ikuko with Dr. Manami. Pipi stands witness alongside Kaguya as Ikuko suffers anaphylactic shock. Following Ikuko's hospitalization, Pipi attempts to console an intoxicated and vengeful Tanaka. Pipi subsequently alerts Kaguya and Tanaka about Ikuko's imminent cremation, spurring Tanaka's rescue.

On the second mission, Pipi assists Kaguya in analyzing Satoshi, a geeky boy whose pent-up emotions disrupt his relationship. After Kaguya's failed attempts to relax Satoshi leave him semi-comatose, Pipi revives him through mouth-to-mouth resuscitation. Pipi later traces despairing tremors alongside Kaguya, pinpointing Satoshi's video game. The two enter the game's software to battle enemies, confronting a tentacle monster embodying Satoshi's repressed soul after his emotional trauma traps him there.

Pipi consistently demonstrates loyalty and attentiveness, supporting Kaguya's interventions by observing critical events, physically aiding distressed humans, and engaging in supernatural battles against the sources of human anguish.