Blue Hour

 (ブルーアワー) is the first digital single by Aida Rikako. It.

The song was named after the time zone when the sky turns dark blue before sunrise. The same as the song "Lotus" from the first album Curtain raise, Jun Ichikawa was responsible for the composition as well as arrangement, and Rikako wrote the lyrics.

In the lyrics of the song, Rikako describes the feelings of facing herself while gazing at the scenery of "blue hour".