The second episode of "Spring of Youth" kicks off with Sa Gye's startling discovery that Kim Bom is the owner of the house he had set his heart on renting a room in. Initially, she hesitates, reluctant to rent to a man, but her aunt persuades her, highlighting the potential benefits of having a renowned renter under her roof. Once a few ground rules are established, Sa Gye makes himself at home.
While exploring his new surroundings, Sa Gye's eyes catch an old photograph of Kim Bom, and he notices the piano in it resembles the one she plays at the restaurant. When she accidentally stumbles, and he catches her just in time, he seizes the moment to inquire about the melody she was humming. She confesses that it's a tune she composed on the piano her mother gifted her on her seventh birthday.
That very night, Sa Gye is haunted by a vivid dream of a younger Kim Bom, her fingers dancing gracefully over the keys of that cherished piano. Later, while Bom is working at a store, the manager informs her that Sa Gye's label has recalled all products featuring his image. Sa Gye's unexpected arrival prompts her to scold him for not defending himself, unaware that the video of him confronting those students was a fabrication.
At school, Sa Gye embarks on a quest to find new bandmates. His search leads him to encounter the two students who had previously caused him trouble, now sporting fake injuries. He senses their involvement was orchestrated by someone else, but they remain tight-lipped about the culprit. The boys flee and report back to Kang Seok-hee, who works under Jo Sang-heon's command. Sang-heon instructs Seok-hee to engineer a wedge between Sa Gye and Kim Bom.
Seok-hee delegates this task to the same boys, who orchestrate a protest against Sa Gye at the university. Faced with this dilemma, the school chancellor challenges Sa Gye: secure 300 sign-ups for his music club if he wishes to stay, or he must vacate his position. Moreover, Sa Gye catches a glimpse of the chancellor receiving a call from Jo Sang-heon, hinting at deeper undercurrents within the university's hierarchy.
Meanwhile, Kim Bom catches wind of the protests and marches resolutely towards Jo & Jo Entertainment's office. There, she confronts Sang-heon, who is taken aback to learn that his company has acquired songs from her. She unveils the truth, asserting that the video featuring Sa Gye was a meticulously crafted forgery. Sang-heon, however, remains unconvinced, insisting that Sa Gye stands alone in this ordeal.
In the medical department's dissection room, Tae-yang grapples with the task at hand, his efforts to focus on the intricate details of his dissection hindered by inner turmoil. His father, the esteemed director of Hanju University Hospital, later looms over him, urging him to abandon his musical aspirations and devote himself solely to medicine.
Sa Gye, undeterred, returns to the makeshift stage he had erected for his nascent band, only to discover it in ruins, the victim of vandalism orchestrated by the same mischievous gang of boys. They taunt him, urging him to throw in the towel. But just as they think they've won, Kim Bom arrives, clad in an unmistakable bear costume, her voice blending harmoniously with Sa Gye's as they belt out his song. She boldly requests to join his band and, with a charm that's impossible to resist, encourages the gathered crowd to lend their names to the cause. Together, they manage to garner an impressive 229 signatures.
The rival boys, incensed, vent their frustration to Tae-yang, who reluctantly agrees to take action. As he observes Bom beaming at Sa Gye during a campus performance, his resolve hardens. Later, with Sa Gye and his compatriots edging closer to their goal with 299 sign-ups, the adversary boys reappear, ready to renew their challenge. But Tae-yang, stepping forward with unwavering determination, adds his name to the list, bringing the tally to a symbolic 300. He confesses that he overheard his bandmates discussing their paid scheme to sabotage Sa Gye, a revelation that has soured his desire to continue working with them.
The chancellor's arrival leaves Sa Gye with no choice but to remain, and eventually, the actual lineup of the band solidifies with Sa Gye, Bom, Gyu-ri, Tae-yang, and their former bandmate Jin-gu. Together, the quintet ventures out for a meal, where their camaraderie shines through, culminating in a playful cake fight that brings their bond to life.
Just as their evening winds down, Sa Gye receives a call from Yoon Seung-su of Jo & Jo Entertainment, who reveals the confidential discussion between Bom and Jo Sang-heon. As they exit the restaurant, Sa Gye catches a glimpse of a photographer snapping their picture, but the individual flees before Sa Gye can confront them.
With their minds set on academics, the group heads to the library, albeit Sa Gye, whose thoughts wander from textbooks to the incriminating evidence pointing towards Jo Sang-heon. Tae-yang returns home to confront his father's fury over missing a surgery due to his band commitments. In a fit of anger, his father shatters Tae-yang's guitar and orders him to leave if music is his true passion. Taking his father at his word, Tae-yang storms out and seeks refuge at Bom's house, ultimately convincing Sa Gye to share a room with him.
Elsewhere, Jo Sang-heon is haunted by a vivid dream from six years past, where he nods off at the wheel on a rainy night, leading to a catastrophic accident. The dream jolts him awake at the precise moment of 5:45 AM.
The next morning, the band members discover a potential new rehearsal space, albeit in dire disarray. While the others abandon the messy site, Bom and Sa Gye roll up their sleeves and tackle the cleanup. Amidst the dust and debris, a curtain falling over them creates an intimate moment shared between the two. Not long after, Sa Gye receives a call from Jo Ji-na, praising the song she acquired from Kim Bom for its exceptional quality.
Bom then embarks on her journey to her part-time jobs, informing Sa Gye that she wouldn't be able to join the band practice but assured him she would diligently practice on her own. As she heads to the restaurant, her heart sinks upon realizing that the piano has been sold, and her boss informs her that her employment there has also come to an end. Devastated but determined, she returns home to find the piano mysteriously awaiting her on the rooftop. Sa Gye reveals that he purchased it as an investment in her future, urging her to come and practice with him. Together, they immerse themselves in the melodious symphony, but their harmonious bond is abruptly shattered when Sa Gye spots Kang Seok-hee snapping photos of them once again.
Sa Gye, fueled by frustration, seeks out Sang-heon for a confrontation. He proposes a drinking contest, wagering that if he emerges victorious, Sang-heon must answer all his queries. After consuming several rounds of drinks, Sa Gye unexpectedly bows to Sang-heon and departs, leaving everyone in bewilderment.
During his cab ride home, Sa Gye's mind is flooded with vivid fragments of his past. Kim Bom, concerned for his well-being, discovers him stumbling home under the influence of alcohol. In a moment of tender vulnerability, he embraces her tightly and whispers, "My Bom Bom," a phrase deeply etched in Bom's heart from her mother's loving lips, thus concluding the second episode of "The Spring of Youth" on a poignant note.
