Episode 3 of Weak Hero Class 2 picks up right where the chaos left off. Park Hu-min—better known as Baku—lays down the law: when wearing the Eunjang High uniform, fighting is strictly off-limits. With a commanding tone, he sends the bullies on their way.

In the aftermath, Hyun-tak apologizes to Si-eun for the misunderstanding that nearly led them to fight. True to form, Si-eun says nothing, quietly walking away. Jun-tae rushes after him, trying to console Si-eun about the rumors that he ruined someone’s life. Si-eun’s response is stark: the rumors aren’t lies, and that’s precisely why he avoids fighting—because he knows the damage he’s capable of.

The next day, Hu-min returns from his suspension, greeting his classmates with a big grin and loud hellos. But the light-hearted mood doesn’t last long. In class, Hu-min has a serious conversation with Hyun-tak: he’s organizing a practice match against Ganghak High. Hyun-tak immediately worries—Ganghak plays basketball like it’s mixed martial arts, and injuries are almost guaranteed.

Before they can talk further, Si-eun, Hyun-tak, Jun-tae, and Hu-min are summoned to the teacher’s office. They’re accused of violently beating Hyo-man’s gang, who have all mysteriously skipped school. In a comedic moment, Hu-min misuses the word “acquisition” instead of “accusation,” showing his usual goofiness. Despite their protests that they were merely defending themselves, the teacher punishes them with mandatory volunteer work over the weekend.

Later, Jun-tae fills Si-eun in on the dark web of alliances forming behind the scenes. He explains the Union—an organized gang made up of delinquents from neighboring schools like Yeoil High, Ganghak High, and Yeosung High. Hyo-man, desperate to prove himself, began collecting stolen phones to offer to the Union leaders. But Hu-min stood in his way, protecting Eunjang students and violently putting down any Union members who crossed the line.

In retaliation, the Union began targeting any student wearing the Eunjang uniform. The Union leaders soon realize Hyo-man is failing to control Eunjang High. Baek-jin, the formidable leader of the Union, orders action against Hu-min. Listening in from the sidelines, Seong-je prepares for the next move.

Meanwhile, during their weekend volunteer service, a slow but genuine bond forms between Si-eun, Hu-min, Hyun-tak, and Jun-tae. Hu-min’s quirky behavior and his endless bickering with Hyun-tak eventually make Si-eun crack a rare smile. Over lunch, a minor accident—a spilled sauce on Si-eun’s hoodie—leads Si-eun to step out to clean up.

Outside the restroom, he encounters Seong-je. Coldly, Seong-je snaps a picture of Si-eun and tries to intimidate him. When Si-eun stares him down without flinching, Seong-je lashes out, but Si-eun effortlessly dodges his punches. Seeing Si-eun eying a flower pot as a potential weapon, Seong-je backs off. On his way out, Seong-je runs into Hu-min and teases him, suggesting that he and Baek-jin are like lovers having a spat.

Meanwhile, we learn more about Baek-jin. Despite being the Union’s leader, he’s no thug in appearance—he’s a top student at Yeoil High, winning academic awards and keeping up a pristine image. As he studies, money from their illegal activities floods into his account. Later, Seong-mok calls to update him: the payments are complete, and Hyo-man wants a meeting.

At the meeting location, Hyo-man and his gang foolishly try to ambush Baek-jin, believing he’s just a “smart kid.” Baek-jin swiftly and brutally demolishes them all, revealing he’s not just a brain—he’s a force to be reckoned with.

After their volunteer work wraps up, Hu-min invites Hyun-tak and Jun-tae to his father’s restaurant for fried chicken, deepening their bond. Meanwhile, Si-eun quietly makes his way to the hospital to visit his comatose friend Su-ho.

During his visit, Hu-min calls to check if Si-eun got home safely, still worried about Seong-je’s earlier appearance. Si-eun reassures him that he’s fine.

As always, Si-eun writes a heartfelt message to Su-ho, updating him on everything that happened. But his moment of peace is shattered when Seong-je appears outside Su-ho’s hospital room.

Seong-je cruelly taunts Si-eun about Su-ho’s condition, casually suggesting they step outside so they don’t “disturb Su-ho’s sleep.” Si-eun’s anger boils over—but the real confrontation is just about to begin.