f(x)'s Luna, the OST powerhouse member of her group, has participated in 'The King Loves' OST Part 5, titled "Could You Tell Me".

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The song brings together Luna's clear, melodic voice with a string arrangement, and was first introduced on the August 8 episode of 'The King Loves' during a critical ending scene between the leads - Girls' Generation's YoonA and Siwan. 

Listen to the audio above, and keep your ears open for the OST while you watch 'The King Loves'.