Episode 5 of "Weak Hero Class 2" commences with a poignant flashback to a volunteer day, where Si-eun and Hu-min forge deeper connections. During their heart-to-heart, Hu-min confides in Si-eun, revealing that Hyun-tak, once a taekwondo champion, had his promising career cut short due to a grave injury inflicted by Hu-min. Despite Hyun-tak's apparent forgiveness, Hu-min is consumed by guilt, unable to shake off the weight of his actions. Si-eun, recognizing the parallel in his own life, echoes Hu-min's sentiments, haunted by his role in Su-ho's plight.
In the present timeline, Si-eun awakens in the sanctuary of Hu-min's home. Their narrow escape from the rooftop, with police hot on their trail, had culminated in Hu-min carrying an unconscious Si-eun to the safety of his abode. With tender care, Hu-min dressed Si-eun's wounds and kept vigil until he regained consciousness. In a solemn pledge, Hu-min vows never to allow such perilous situations to recur.
Si-eun, gathering his thoughts, implores Hu-min that resorting to violence is not the solution. He warns of a perpetual cycle of retaliation, ultimately culminating in severe harm. Touched by Si-eun's words, Hu-min resolves to put an end to his grudge against Baek-jin by acknowledging his defeat.
An unexpected twist unfolds as it is revealed that Baek-jin and Hu-min share a history as childhood friends. In their younger years, Hu-min had been Baek-jin's protector, shielding him from bullies.
Elsewhere, Baek-jin picks up Seong-jin from the hospital, not out of concern for his well-being, but to confront him about their burner account. Their destination: a familiar haunt where Baek-jin often metes out justice to disobedient gang members. Baek-jin's probing questions make it clear to Seung-je that his intentions are far from benevolent. Realizing that his trust had been misplaced, Seung-je's anger simmers. Despite their less-than-stellar moral compass, he had considered them comrades in their clandestine alliance.
Seung-je confesses to Baek-jin what he revealed to the police, his voice tinged with disappointment. With a heavy heart, he announces his temporary departure, warning Baek-jin not to search for him. In this moment of betrayal and realization, the fragile bonds of their camaraderie shatter.
The bond among Si-eun, Hyun-tak, Jun-tae, and Hu-min blossoms as they immerse themselves in shared experiences—poring over textbooks at school, engaging in spirited basketball games, and simply enjoying each other's company during leisurely afternoons. However, on one particularly chilly day, Hu-min's tranquil routine is shattered by a phone call from the police station concerning his father's legal woes. He learns that the young boys who initially accused his father of selling alcohol to minors have reversed their testimonies. Now, they claim that his father neglected to verify their IDs, prompting an enraged altercation where he assaulted a minor at the precinct. Upon Hu-min's arrival, he discovers his father confined within a police cell. His anger intensifies as he eavesdrops on the giggling boys outside the station, following them in a haze of fury. Just then, a text from Baek-jin arrives, urging Hu-min to resist giving in to their provocation. Baek-jin warns that he will abandon both Hu-min's friends and his father unless Hu-min agrees to join their union.
Meanwhile, Si-eun steps into his home to find his mother eagerly awaiting his return. She is acutely aware of his absence from cram school and deeply concerned about the marks of conflict etched upon his face. With a heavy heart, she presents him with an overseas school admission, urging him to prepare for departure. Si-eun rejects the offer fiercely, insisting that she leave him to his own devices, much like she had done in the past. His mother's composure crumbles, her voice breaking as she confesses her self-blame for the incidents that marred his previous school life. Her worries for her son overflow, leaving Si-eun to ponder the possibility of leaving.
Meanwhile, Baek-jin relentlessly corners Hu-min, using the safety of his friends and father as leverage in his sinister blackmail scheme. Hu-min, torn between obligation and fear, ceases attending school, leading to a heated confrontation with his father over the matter. To shield his loved ones from harm, Hu-min reluctantly agrees to align with Baek-jin. His initial mission: to coerce Seokham's alpha male, Gorilla, into embracing the union's fold. Hu-min trails Gorilla to a smoky nightclub, where with a single, decisive punch, Seokham High surrenders to the union's dominion.
Elsewhere, Hyun-tak and Jun-tae procure Si-eun's address from school records. On the eve of Si-eun's departure for overseas studies, they descend upon his doorstep, inviting him out for one final basketball session, a cherished ritual among friends. During their game, Si-eun inquiries about Hu-min's absence from school, his concern evident. He dials Hu-min's number, receiving assurances from him that everything will be alright before the call abruptly ends.
Hu-min subsequently arrives at the bowling alley, where Baek-jin and his fellow union members await, ready to formally embrace him into their ranks. As the episode draws to a close, Jun-tae places a call to Si-eun as he stands at the airport, moments from boarding his plane. Through the receiver, Jun-tae imparts words that Si-eun has longed to hear—acknowledging that the misfortunes befalling Hu-min, Hyun-tak, and even their mutual friend Su-ho are not his fault. Touched by this revelation, Si-eun makes a spontaneous decision: he will not leave.
