貴姉 is read as きし (kishi) and means you.
きし
kishi
あねき
elder sister
たっとい
noble
きじん
aristocrat
きちょう
precious
きぞく
きちょうひん
valuable article
きしゃ
your company
あなた
you
きひん
noble visitor
ききんぞく
precious metal
きふじん
lady
きこうし
princely young man