東ノ暁 西ノ黄昏 (Higashi no Akatsuki, Nishi no Tasogare)

Background
The song was first uploaded on January 1st 2009; it reached Nico Hall of Fame (exceeding 100,000 views). It's Shigotoshite-P's second duet song using Kaito and Meiko; the first being Tsugai Kogarashi.

Although it's not stated in Shigotoshite-P's description; many can hear Kaiko's voice somewhere in the background (there are Shigotoshite-P's works where she uses Kaiko as the vocal)

The song has various and no fixed meaning; Kaito can be interpreted as the moon; who can never see Meiko the sun. Whenever Kaito rises up to shine, Meiko, the sun, falls on dusk; and vice versa. This goes on for eternity, where the sun and the moon can never ever meet.