Weak Hero Class 2 Episode 4 dives straight back into the tension. After Seung-je ominously asks Si-eun to follow him, he leads him all the way to a bowling alley—the hidden base of the Union. There, Si-eun finds himself in Baek-jin’s office. Without even glancing up, Baek-jin coldly tells Si-eun to wait.

But Si-eun isn’t there for conversation—he’s there to send a message. With chilling calm, Si-eun warns Baek-jin: if his people ever approach Su-ho again, he will kill them all. Before leaving, Si-eun even helps Baek-jin solve a difficult math problem, a final display of control and contempt. Baek-jin doesn’t push back; instead, he simply asks Si-eun to distance himself from Hu-min.

Later that night, Baek-jin makes his next move. He sends his boys to Hu-min’s father’s restaurant, where they use fake IDs to buy alcohol, then call the police, framing Hu-min’s father for selling alcohol to minors. A neighbor alerts Hu-min, who rushes to the scene, devastated. Soon after, Baek-jin texts Hu-min an address—summoning him to a meeting the next day.

The following morning, Si-eun tells Hu-min that he no longer wants to be involved. He prefers to be alone, unwilling to get dragged deeper into the brewing war between Hu-min and Baek-jin.

After school, Si-eun leaves early for cram school, while Hu-min lies that he has a “date”—really, he’s heading to meet Baek-jin. Meanwhile, Seung-je and the Union gang set their trap, tasked with hunting down Hyun-tak, Jun-tae, and Si-eun.

Si-eun encounters a Ganghak High group, but they let him pass, honoring Baek-jin’s order to leave him alone. Jun-tae and Hyun-tak, however, aren’t as lucky. They run straight into Seung-je’s group. Hyun-tak selflessly tells Jun-tae to run while he stays behind to fight. Although Jun-tae manages to slip away long enough to call Si-eun, he’s quickly recaptured.

Hearing Jun-tae’s plea, Si-eun ignores his warning and rushes back to help.

At the bowling alley, Hu-min arrives for his meeting. He easily intimidates the Union members downstairs into giving him directions to Baek-jin’s office. Baek-jin calmly pitches his offer: he wants Hu-min to join the Union, promising to turn it into a profitable “business” after graduation.

Hu-min calls Baek-jin a fool, refusing the offer without hesitation. But then Baek-jin’s trap becomes clear—this meeting was just a distraction to isolate Hu-min from his friends. Realizing it too late, Hu-min rushes out. Union thugs try to stop him, but he demolishes them without breaking a sweat. Baek-jin steps aside, pretending to let Hu-min leave, but Hu-min is quick to set the record straight: it’s not that Baek-jin let him go—it’s that Hu-min chose to spare them.

Meanwhile, on a rooftop elsewhere, Seung-je gleefully beats Hyun-tak while the other gang members live-stream the assault. Jun-tae can only watch in horror, unable to intervene.

Si-eun gets the rooftop location from some students talking about the live-stream. Without hesitation, he sprints to the scene—arriving just as Seung-je poses for a humiliating “victory photo” over the battered Hyun-tak and Jun-tae.

Si-eun attacks Seung-je without a word. Although Seung-je initially has the upper hand in sheer strength, Si-eun’s style is vicious and calculated. In a brutal move, Si-eun smashes Seung-je’s glasses and uses the broken frame to stab him in the foot.

The rooftop battle intensifies. No matter how hard Seung-je hits, Si-eun keeps rising to his feet, his eyes burning with defiance. Seung-je, excited by the challenge, decides to go for a fatal blow—but Si-eun anticipates him, and they both collapse from exhaustion after a desperate final clash.

As sirens wail in the distance, Hu-min finally arrives. He rushes to Si-eun’s side. In his dazed state, Si-eun mistakes Hu-min for Su-ho. Tearfully, he confesses that he got into another fight and apologizes, before losing consciousness in Hu-min’s arms.