KAITO is a Vocaloid DTM (Desktop Music) software created by Crypton Future Media. He utilizes the older Vocaloid engine developed by YAMAHA, the predecessor of Vocaloid2. The voice was supplied by a Japanese male singer Naoto Fūga (風雅 なおと, Fūga Naoto). The product's name was invited from the public, and "KAITO" was selected from among applicants, which was the idea of Shu-tP.
via Wikia - Kaito
This is a fanmade AMV and this video is took from Anime Samurai X. I really like this song.
This video is about Shion Kaito and his cousin Harune Sora. This video is also a fanmade video.
Finally, This song is a fanmade video but is a Chinese song called "纺歌" (same with "Tsumugi Uta"). She has a nice beautiful sound of singing.