I Am You, You Are Me (Our Secret Diary) - Single

I Am You, You Are Me (Our Secret Diary X LEE SEOYEON)

우린 마지막 봄인가 봐 (I Guess It's Our Last Spring)

너는 나 나는 너 (말하고 싶은 비밀 X 이서연 (프로미스나인))

I Am You, You Are Me (Our Secret Diary X LEE SEOYEON) (너는 나 나는 너 (말하고 싶은 비밀 X 이서연 (프로미스나인)))

I Guess It's Our Last Spring - Single

I Am You, You Are Me (Our Secret Diary) - Single