Dongsaengui Uimu

Dongwoo, who happened to find the secret of his squad leader is spending a hellish day because of it. Jungyeon, the younger sister learns of her brother’s suffering through his diary. To protect her brother whom she loves more than anyone else, Jungyeon visits Yoo Jinho, the squad leader… “Oppa… I’ll protect you this time.”

(Source:TOPTOON, translated and edited)