Yoosung is a very nice and lovable college student, and is described by the other RFA members as "a real puppy." Yoosung cares about people a lot and loves to spend time with others. He is naive and believes things that are told to him more often than not, as shown in several of his interactions with 707. As a result, he is often the target of 707's pranks and teasing. Even so, he considers 707 to be his closest friend, and the pair are frequently seen bonding over video games and their love of junk food.

Despite his somewhat naive and lighthearted nature, Yoosung became severely depressed after the death of his cousin, Rika, who he idolized and was very close with. After her death, Yoosung lost all interest in his studies and became a shut-in, rarely leaving for classes and opting instead to play LOLOL in order to cope with the crippling sadness. However, at his core he is a generally kind and bubbly person, if a bit childish at times.

During Yoosung's route, 707 states in a phone call with the MC that Yoosung had yandere tenancies, which the player can encourage (along with pretending to be his dead cousin, Rika) in order to get a bad ending. However, outside of this ending, he portrayed as a sweet person aside from mild possessiveness and the tendency to hold a grudge.

Voice quality: High-medium pitched. A little bubbly, and at times loud and enthusiastic.

Voice reference: https://www.youtube.com/watch?v=4sW-FTxmq5E