Himeji Wakaba is a 5th-grader who possesses a unique ability to see supernatural entities that are invisible to others. However, this gift often brings misfortune to those around her, leaving Wakaba lonely and despondent. Despite her inclination to take in lost creatures, her parents make her get rid of them. But upon seeing their child's distress, they promise her that she can keep the next creature she brings home.
Suddenly, a cheerful pink monster named Pupipo materializes out of nowhere. Although the family is bewildered by Pupipo's origin, they honor their promise to Wakaba and allow her to keep the new addition. Pupipo quickly becomes Wakaba's most loyal companion, protecting her from any dangers and helping her connect with a fellow student who shares her supernatural interests. Together, they stand up to bullying and bring brightness to Wakaba's life. Through Pupipo, Wakaba finally finds the friend she's always needed.