Yoo Si Jin

Yoo Si Jin (유시진) is one of the main characters of the Descendants of the Sun series. He serves the Republic of Korea Armed Forces as an army Captain (later promoted to Major). He was a highly competent soldier who possessed excellent judgement and reasoning skills, thus earning him a position as the team leader of the Alpha Team, an elite special forces unit serving South Korea trusted to handle extensive missions requiring advanced personnel.

Biography
Yoo comes from a family with a military background. His father is a retired Command Sergeant Major and his mother is deceased.

After graduating in the Korea Military Academy (KMA) with honors, Yoo pursued his career to become a soldier. Righteous, courageous, and obedient, Yoo held high expectations for his commanding officers and was eventually promoted to Captain.

Personality
Yoo maintained his strongly held principles as a soldier no matter the situation. He always knew what was right or wrong, and acted upon his beliefs of maintaining peace and order. He is a diligent, hard-working and sometimes witty character who used his comical personality to cheer people up.

Kang Mo Yeon
Girlfriend

Seo Dae Young
Close friend

Yoon Myung Ju
Seo's girlfirend