Episode 12 of "Bad-Memory Eraser" unfolds with a thrilling rescue scene, as Ju-yeon and Shin swiftly pull Gun from the brink of danger in the pool, his life hanging by a thread. However, it's Sae-yan who unexpectedly arrives at Gun's doorstep, transforming into a makeshift nurse amidst her own clumsiness, determined to nurse him back to health from his feverish state. Confusion etches on Gun's face as Sae-yan, despite her inexperience, endeavors to provide solace and care. She reveals her ulterior motive—a prepayment for Gun's services in searching for her biological father once he's fully recovered.
Meanwhile, Ju-yeon finds herself adrift at home, an unwanted presence neither at the Athlete's Village nor at the hospital where she's taken leave. Her idleness only adds to her restlessness. At the hospital, Han's heart still bears the brunt of Nurse Song's words, his spirit bruised. As the staff arranges their next excursion, Han finds himself the subject of self-deprecation, his loneliness palpable. Nurse Song attempts to include him in their plans, but Dr. Yeo, oblivious to the undercurrents, dismisses him, assuming he's occupied.
In Gun's modest abode, Sae-yan busies herself with cooking, her voice crackling over the phone as she updates Ju-yeon on Gun's progress. Ju-yeon's intricate web of avoidance becomes clearer—she orchestrated Sae-yan's presence, yet distances herself from Gun's world. When Gun overhears the call and yearns to speak with Ju-yeon, Sae-yan's quick intervention ends the conversation abruptly.
Ju-yeon, entrenched in domestic chores, ignores Shin's persistent calls, her mind a whirlwind. Her wandering gaze lands on Gun's discarded diary, a testament to his unfiltered emotions, largely shrouded in melancholy. Shin's gestures of brotherly love, sending him trophies from his victories, only serve to deepen Gun's sense of inadequacy, feeling as if his elder sibling is mocking his failures.
Memories of his military days resurface, where Gun sought solace in reminiscing about his first love, a beacon of hope amidst the monotony. The bitter irony lingers—they share the same birthday, yet their parents' celebrations exclusively revolve around Shin. Gun's fears manifest—would his first love, too, forsake him if they were reunited? This haunting question keeps him from pursuing her, a wall of self-doubt towering between them.
As for Shin, he's embroiled in a relentless search for the individual who captured their confrontation on the bridge, the images a stark reminder of their fractured bond. CEO Hong joins the hunt, speculating that the perpetrator is a gambler, possibly angling for Shin's influence to manipulate a match. The stakes are high, and the web of secrets and motives tightens its grip around each character, setting the stage for a dramatic turn of events.
Sae-yan persists in nurturing Gun, her gaze inevitably lingering on his captivating good looks. Yet, her affections are unrequited, as he solely yearns for Ju-yeon, concocting excuses for Sae-yan to reach out to her. Seizing the phone, he finally connects with Ju-yeon, who reassures him that Sae-yan, with her kinder heart, is the perfect caretaker. Hanging up, Ju-yeon stands outside Gun's apartment, basking in the warmth of their cherished memories.
Her solitude is fleeting as Shin appears at her doorstep, seeking her out. Mrs. Kyung watches in amazement as he patiently awaits Ju-yeon's arrival, intending to delight her with a surprise. She pulls out her finest china, only to have Seung-hyun, her mischievous grand-nephew, spill tea on Shin's attire. In response, Mrs. Kyung offers him clothes once belonging to her late husband, and Shin vows to return them, pristine, after laundering.
As Shin spends time with Seung-hyun, his curiosity piqued by Ju-yeon's charm, the boy misunderstands and assumes he's inquiring about Sae-yan. Their playful bickering ensues, with Shin insisting Ju-yeon surpasses Sae-yan in beauty. Amidst the chaos, Shin stumbles upon Gun's diary, taking it with him.
Back at Gun's place, Sae-yan endeavors to concoct grappa, an Italian remedy necessitating a touch of brandy. Unconvinced by the small amount, she liberally pours and samples, ultimately polishing off two bottles of brandy. When she presents Gun with the potion, she's intoxicated, the remedy reduced to pure brandy. Sae-yan succumbs to slumber, leaving Gun amused yet dutifully tending to her. With tenderness, he administers hangover relief and pinky-swears to locate her father, as she weeps for him.
Meanwhile, Ju-yeon wanders the town, her spirits dampened, when she crosses paths with a patient who diagnoses her with a heartache so profound that even painful memories are cherished. Arriving home, she finds Shin engaged in a card game with Mrs. Kyung. Irritated, she drags him outside, explaining her avoidance. She believes his kiss was merely to assist Gun, but Shin confesses his genuine affection. Ju-yeon apologizes for misleading him, her heart belonging to another. He suspects her harshness stems from Gun's presence.
Fruitless in their discourse, Ju-yeon attempts to evict Shin. Just then, Gun, visibly ill, arrives carrying an inebriated Sae-yan, desperate to see Seung-hyun. Ju-yeon's concern for Sae-yan is palpable, while Gun's heart aches at her lack of attention. Seizing the moment, Shin gracefully thanks Ju-yeon for their evening and vows to return Mrs. Kyung's clothes, his exit marked by a touch of poignancy.
Gun remains unfazed and dares Shin to a tennis match, his tone tinged with amusement as he comments on Shin's penchant for eyeing his possessions. As they engage in a fierce game, Gun proves himself a formidable opponent, yet Shin manages to steal the first point. Suddenly, Gun's curiosity piques as he inquires about Shin's wristband, unaware that it's the very one that slipped off during the fateful night when he rescued Gun from the bridge. Shin's expression turns to shock, realizing that Gun's memories of that evening are slowly resurfacing. A distant figure, the witness from the bridge, observes the unfolding scene with keen interest.
After the match, Shin takes drastic measures, incinerating Gun's diary, only for the witness to intervene at the last moment, snatching it from the flames. Meanwhile, Sae-yan finds herself in a drunken haze, regaling her companions with tales of Gun, initially painting him as a threat to her sanctuary but ultimately acknowledging their unexpected friendship. Ju-yeon, on the other hand, wears a sorrowful mien, her sorrow manifesting in a painful burn incurred while cooking.
The following day, amidst the bustle of the Athlete's Village, Shin and Sae-yan engage in their customary bickering, with Sae-yan confidently asserting that Ju-yeon's heart belongs to another. Guk-bong, hopelessly smitten with Sae-yan, watches from the sidelines as Shin's attention is abruptly diverted by a mysterious text from the witness, summoning him to a meeting. Shin hastens to the rendezvous point, unaware that Hong's henchmen are tailing him. A peculiar stranger materializes, sparking a brief commotion as the bodyguards pounce, only to discover him a harmless fan. But the real witness remains hidden, fleeting into the shadows. Shin's pursuit leads to a shocking turn of events as he's struck by a car, leaving his knee gravely injured.
Meanwhile, Gun embarks on a journey to the police station, eager to uncover the truth behind his accident. The officer's narration paints a picture of Shin as a selfless brother, leaping into action without hesitation, shoes forgotten, to save Gun. This revelation stirs confusion within Gun, for his memory holds only fragments of Shin choking him and the chill of the water.
As Episode 12 of "Bad-Memory Eraser" draws to a close, Gun finds himself at the bridge, serendipity striking when he discovers a truck parked nearby, its dashcam potentially holding the key to his past. Just as he's about to unravel the mystery, Guk-bong's panicked voice interrupts, informing him of Shin's disappearance. Gun sets out to find his friend, unaware that Ju-yeon is consumed by fear, Seung-hyun's revelation that Shin has taken Gun's diary sending her into a state of distress.
