Shadow Star☆(1998)

Narutaru

Shiina Tamai, an energetic sixth-grader, found a star-shaped creature on the seabed during her visit to her grandparents' house. She befriended it and found it has some supernatural powers, such as flying and incredible strength. However, what seemed like a dream may turn out to be her worst nightmare as she meets other kids who have similar creatures and dark, destructive desires...

Note: Includes an extra chapter.