During her summer holiday at her grandparents house Tamai Shiina, a young and cheerful schoolgirl, meets a strange looking creature. They befriend each other and Shiina names it "Hoshimaru - The Round Star". When Shiina returns home after the summer to go back to school she starts meeting other kids that also have befriended a strange creature like Hoshimaru. But she soon finds out that not all these creatures and their masters are as friendly as Hoshimaru.

(Source: Anime News Network)

 AnimeRulz is the best site to watch Shadow Star Narutaru SUB and DUB in HD quality.