Pemeran Why R U?

Lee Jung Min

as Jung Lee Won

Pemeran Utama

Lee Ye Hwan

as Kim Ji Oh

Pemeran Utama

Lee Sang Min

as Woo Sun Woo

Pemeran Utama

Park Chang Hoon

as Ko Yu Gyeom

Pemeran Utama

Jeon Sa Ra

as Kim Do Yeon

Pemeran Pembantu

Jo So Young

as So Young

Pemeran Pembantu

Lee Da Won

as Da Won

Pemeran Pembantu

Park Young Un

as [Yu Kyeom's Junior]

Pemeran Pembantu

Su Hyun

as Jung I Jin [I Won's sister]

Pemeran Pembantu

Kim Na Hyun

as Kim Na Hyeon [Professor]

Pemeran Pembantu

Nat Natasit Uareksit

as [Himself] (Ep. 1)

Bintang Tamu

Max Kornthas Rujeerattanavorapan

as [Himself] (Ep. 1)

Bintang Tamu

Kim Dong Kyu

as Kim Dong Kyu [Profesoor] (Ep. 4)

Bintang Tamu

Bang Jin Won

as [Unknown classmate] (Ep. 5)

Bintang Tamu

Kim Eun Hye

Sutradara

Seo Ji Eun

Screenwriter