Title: Everlasting (it’s you)
Vocals: witch
Lyrics: witch
Arrangement: sou
Album: Sparkle!
Circle: Sound CYCLONE
Original: 懐かしき東方の血 ~Old World /月まで届け、不死の煙 (東方永夜抄)
This is witch’s version from the album Sparkle! There’s a version by しゃばだば from the album 東方モテタイ, which has different lyrics.