Hunter x Hunter OST - Biscuit Krueger Theme/UNRELEASED OST [Violin/Piano]
"Biscuit Krueger Theme" on violin and piano.
Composer: Yoshihisa Hirano (平野 義久 Hirano Yoshihisa)
From Hunter × Hunter/HUNTER×HUNTER ハンターハンター
Performer: Ranno Tamm
Arrangement: Ranno Tamm
Sheet music: https://goo.gl/34N4dV
So basically, the never released that theme, so i just listened to it, wrote it down, and played it.