I played this song a while ago, but finally got around to finishing up sheet music for it. This is Time of Silence (静寂の時, “Seijaku no Toki”) from the anime Utawarerumono (うたわれるもの), composed by Hijiri ANZE (安瀬).
Seijaku no Toki (from Utawarerumono / うたわれるもの)
PDF
Sibelius
MIDI