Class: Mage
Relative(s): Park Kyung-Hye (Mother), Sung Jin-Ah (Sister), Sung Il-Hwan (Father), Cha Hae-In (Wife), Sung Su-Ho (Son), Yoo Jin-Ho (Brother in Law)
Guild: Ahjin Guild (Guild Master)
Affiliation: Korean Hunters Association (helper), White Tiger Guild (helper), Hunters Guild (helper), Knights Guild (helper), Ahjin Guild (Guild Master)

Seong Jin-U is the protagonist of Solo Leveling and is known as an infamously weak E-Rank Hunter. He is a humble and benevolent individual who cares deeply for his family and has an ardent desire to become stronger. As a result, he shares a close relationship with his sister and his mother, and rarely wastes an opportunity to refine his skills and gain more power.

He becomes an S-Rank hunter after being given a chance to become stronger by the System.