In episodes 3 and 4 of Eccentric Romance, Jay and Seung Hoon are assigned a group project alongside Gi Hyun and Seung Hui, a YouTuber. Seung Hoon is named group leader, but from the start, his jealousy flares up as he watches Jay interact with Jin Wook at the gym.
During a playful moment in the showers, Jin Wook joins Jay and Seung Hoon, and Seung Hoon notices a scar on Jin Wook’s back, adding to his growing suspicion. Later, Seung Hoon suggests that Jay stop training with Jin Wook and train with him instead, offering to slash his fees in half. Jay agrees, but his phone accidentally breaks during their playful sparring. Needing money to fix his phone, Jay quits training with Jin Wook, which pleases Seung Hoon.
Their training intensifies, but Seung Hoon becomes increasingly suspicious of Jin Wook after overhearing a strange phone call. Seung Hoon’s jealousy over how close Jay and Jin Wook have become escalates, especially when Jin Wook suggests Jay volunteer and picnic together. Seung Hoon confronts Jay, asking if he likes Jin Wook. Jay admits his feelings, leaving Seung Hoon uneasy and confused.
Meanwhile, the recent murder still circulating, unnerves Jay, especially when Seung Hui reveals the victim was a student from their school. Seung Hoon takes charge of the group, assigning them to clean up trash around the school, but things get tense when Seung Hoon coldly brushes off Jin Wook at the gym, pulling Jay away. Jin Wook’s friendly expression turns dark as they leave, hinting at deeper mysteries.
When they run into Gi Hyun and Seung Hui, who also know Jin Wook, Jay jokes about their “coincidental” meetings and meeting the killer coincidentally but he is immediately warned by Seung Hoon not to take the situation lightly. The tension between Jay and Seung Hoon grows as Seung Hoon insists that Jay is letting his guard down, potentially making him the killer’s next target. The argument escalates until Seung Hoon takes Jay home, where he expresses his deep suspicion of Jin Wook. Jay dismisses it as jealousy, leading to an argument that causes them to ignore each other at school.
Later, Jay confides in his friend Ji Won, who advises him to take Seung Hoon’s concerns more seriously, as Jay tends to trust people too easily. During a volunteer session, Jay asks Seung Hui about Jin Wook’s character, and Seung Hui describes him as mysterious, fueling Jay’s curiosity even more.
When Jay and Jin Wook plan to hang out, Seung Hoon overhears and suggests they spy on Jin Wook’s volunteer work. They observe the group, but nothing seems suspicious. Jay apologizes for his earlier behavior, cautioning Seung Hoon against making accusations without proof. Their spying is discovered, and they have to join the others. Jin Wook offers them food, but they refuse since they didn’t volunteer.
As they leave, Seung Hoon admits he might have been wrong about Jin Wook and promises Jay that he’ll treat him better from now on. However, the episode ends on a chilling note as Seung Hoon discovers a bloodstained sickle hidden in the gym storeroom, hinting that the mystery is far from over.
