Pemeran Blue Birthday

Ye Ri

as O Ha Rin

Pemeran Utama

Yang Hong Seok (양홍석)

as Ji Seo Jun

Pemeran Utama

Lee Sang Jun

as Cha Eun Seong

Pemeran Utama

Kim Gyeol Yu

as Do Su Jin

Pemeran Pembantu

Park Joo Hyun

as Kim Ui Yeong

Pemeran Pembantu

Lee Dong Joo

as Kim Sin U

Pemeran Pembantu

Jeong Ye Dam

as Ji Hye Min [Young]

Bintang Tamu

Kim So Yoon

as O Ha Rin [Young]

Bintang Tamu

Park So Jung

as Do Su Jin [Young]

Bintang Tamu

Moon Joo Won

as Ji Seo Jun [Young]

Bintang Tamu

Song Min Hyung

as [Photo shop owner] (Ep. 1-2, 10, 16)

Bintang Tamu

Yoo Soo Bin

as [Senior at Seoyeon High School] (Ep. 3)

Bintang Tamu

Lee Byung Jae

as [Detective] (Ep. 9)

Bintang Tamu

Moon Sang Hoon

Bintang Tamu

Park Dhan Hee

Sutradara