Cast from Why R U?

Lee Jung-min

Jung Lee Won

Lee Sang-min

Woo Sun Woo

Park Chang-hoon

Ko Yoo Kyeom

Lee Ye-hwan

Kim Ji Oh

Jeon Sa-ra

Kim Do Yeon

Jo So-young

So Young

Dawon

Da Won

Park Young-un

[Yu Kyeom's Junior]

Kim Na-hyun

[Professor]

Su Hyun

Jung Lee Jin [Lee Won's Sister]

Natasitt Uareksit

[Himself]

Kornthas Rujeerattanavorapan

[Himself]

Kim Dong-Kyu

[Professor]

Bang Jin Won

[Unknown Classmate]