The opening scene of Episode 1 of "Spring of Youth" unfolds with a youthful boy, Sa Gye, diligently honing his dance steps when an unforeseen mishap occurs—his partner's stick inadvertently strikes him in the eyes. Plunged into darkness, Sa Gye's world momentarily crumbles, yet a miraculous cornea transplant restores his vision, setting the stage for his ascent to fame as a member of the esteemed band, The Crown.
The narrative shifts to one of the band's electrifying concerts, followed by an extravagant bash celebrating their triumphs. Amidst the revelry, Sa Gye indulges heavily in alcohol, only to be suddenly assailed by haunting fragments of a memory involving a rain-slicked street and a car. Retreating to his bed, his voice narrates a haunting recurring dream of a maiden accompanied by a distinctive melody. Curiously, his eyelids flutter open at the precise moment of 5:45 AM each dawn.
However, the narrative takes a darker turn when Yeon Seung-su, an employee of Jo & Jo Entertainment, pays him a visit with troubling news: while intoxicated, Sa Gye allegedly assaulted the company's CEO, Jo Sang-heon. The incriminating footage has spread like wildfire across social media, leaving the CEO hospitalized. Sa Gye rushes to the company headquarters, where a chance encounter with Kim Bom, a young girl whose necklace inadvertently drops, reveals a small music box pendant playing the very melody haunting his dreams. Though he hears the tune, his blurred vision prevents him from tracing its source.
At the office, he is handed a directive to take a two-month hiatus from the band and attend Hanju University, where he maintains a technical student status. Meanwhile, Kim Bom crosses paths with Ji-na, an employee at Jo & Jo Entertainment and Jo Sang-heon's daughter. Ji-na expresses interest in acquiring Bom's song for the company, to which Bom agrees, albeit with a scathing remark appended to the contract about the paltry payment.
Bom returns to her abode, where she resides alongside her aunt and cousin. We come to understand that her aunt has secured a loan against their house, leaving them in dire need of funds to repay it. In the hospital setting, Jo Sang-heon reminisces about the assault orchestrated by Sa Gye, who accused him of witnessing Sang-heon's past deeds six years prior. Meanwhile, oblivious to that fateful night, Sa Gye ventures to Hanju University. A sudden downpour ensnares him and Bom, causing her necklace to plummet once more. This time, Sa Gye deciphers the origin of the haunting melody and inquires about it from Bom. She reveals it as her own composition before departing with her friend, Seo Tae-yang, who arrives with an umbrella to her rescue.
It soon transpires that Tae-yang harbors a secret admiration for Bom. The following day, Sa Gye is greeted by an enthusiastic crowd of admirers on campus. Escorted by Gyu-ri to the theater and film department, Sa Gye delivers an abysmal performance of Hamlet. In the subsequent days, he lavishly spends his money around the university. In contrast, Bom renovates one of the house rooms and transforms it into a rental space to contribute towards repaying the loan.
Through another student, Sa Gye discovers that Kim Bom works part-time at a restaurant. He tracks her down, but she repeatedly evades him, reluctant to engage in conversation. Their encounter is once again interrupted by Tae-yang, who physically halts Sa Gye's persistence by flipping him over his shoulder. Nevertheless, Sa Gye finds his way to the music department and learns that Bom and Tae-yang are members of a band seeking new recruits. He applies to join and finds himself in a heated dispute with Tae-yang, a.k.a. the university's own Sa Gye. They decide to settle their difference through a musical duel. Bom even agrees to share the story behind her song should Sa Gye emerge victorious. Tae-yang showcases his versatility with various instruments, while Sa Gye impresses with his guitar skills. However, he surrenders when a guitar string snaps,宣布 Tae-yang as the triumphant victor.
Elsewhere, Jo Sang-heon embarks on an inquiry regarding a certain individual, only to receive a series of photographs featuring Kim Bom. The investigator reveals to him that Sa Gye appears to hold a close bond with her. At the university, Sa Gye posts a notice in search of fellow band members, his enthusiasm palpable. Subsequently, he ventures to Bom's restaurant and is captivated by her mesmerizing piano playing. After her shift concludes, he persistently urges her to join his band, an encounter that Jo Sang-heon witnesses from afar.
Later that evening, Sang-heon pays a visit to Sa Gye, presenting him with an ultimatum: either enlist in the military or pursue studies abroad. Sa Gye, steadfast in his resolve, refuses both options, prompting Sang-heon to sever ties with him. The following day, Tae-yang's bandmates orchestrate a prank on Sa Gye, capturing a misleading video that portrays him as attacking them. The controversy escalates, forcing Sa Gye to issue a public apology and relinquish his position in The Crown. Desperate to settle the cancellation fees, he sells his house and belongings.
With his mother residing in the United States, Sa Gye wanders the streets until he finds himself at Bom's doorstep. Memories of the place flood back, evoking a sense of nostalgia. Noticing the renter's sign, he engages in conversation with the landlord, who turns out to be none other than Kim Bom herself.
The epilogue of Spring of Youth Episode 1 depicts Bom and Tae-yang walking away after their encounter with Sa Gye. Suddenly, Bom bolts back, searching for him. It transpires that she recognized him from a concert she attended at Gyu-ri's insistence. Entranced by his performance, she was particularly moved when Sa Gye tossed a soft toy into the crowd, pronouncing that whoever caught it could go on a date with him. Fatefully, the toy landed in Bom's hands.
