Hameln no Violin-hiki Gaiden: Sorekara...
Violinist of Hameln Gaiden
ハーメルンのバイオリン弾き 外伝 それから…
A special oneshot which serves as a sequel to the original Hameln no Violin Hiki manga series and as a prequel to the new series Hameln no Violin Hiki - Shchelkunchik.
-MangaUpdates