Niji no Kakera

"Niji no Kakera" (虹のかけら) is a song performed by Natsumi Kon. It was used as the first opening theme for the 2014 television anime One Week Friends (Isshuukan Friends / 一週間フレンズ。), which was animated by Brain's Base.

The song was released on May 21, 2014 as Kon's debut single through FlyingDog and Victor Entertainment. Yuho Iwasato wrote the lyrics, Kawano Kei composed the music, and toku arranged the track. The CD single also included the songs "Watashi wa Sō Omowanai" and "Tokyo no Yoru wa Naiteru".