The twelfth episode of Bad-Memory Eraser starts with Ju-yeon and Shin saving Gun from the pool. Nevertheless, it is Sae-yan who arrives at Gun’s house and takes care of him while he is sick. He is bewildered while Sae-yan is awkward but tries her hardest to look after him. She informs him that she is paying him in advance to search for her natural father once he recovers.
As he ponders Ju-yeon’s whereabouts, she is causing trouble at home since she is not required at the Athlete’s Village and has also taken a break from the hospital. Meanwhile, Han is still injured emotionally by Nurse Song’s remarks while at the hospital. While planning their next outing, he mocks himself. The song attempts to involve him, but a busy Dr. Yeo dismisses him, believing he has too much going on.
While Sae-yan prepares food for Gun, she keeps Ju-yeon informed about his well-being. We discover that Ju-yeon asked Sae-yan to take care of him and makes every effort to steer clear of him. Upon hearing the phone call, Gun attempts to communicate with Ju-yeon but Sae-yan disconnects the call. Ju-yeon resumes doing chores around the house and continues to avoid answering Shin’s phone calls. She finds Gun’s journal that Sae-yan had thrown away.
He talks about his genuine, mostly sorrowful experiences in the writing. Shin sends trophies he wins to Gun, making Gun feel like his brother is taunting him. While serving in the military, he occupied himself by reminiscing about his first romantic relationship. Both siblings share the same birth date, however, their parents only acknowledge and celebrate Shin’s birthday. Gun is afraid to see his first love because he questions if she would leave him too if they were in a relationship.
In the meantime, Shin is actively searching for the individual who captured photos of him strangling Gun on the bridge. CEO Hong is handling the situation and has a hunch that the man is a gambler who wants Shin to manipulate a match.
Sae-yan still looks after Gun and can’t help but admire his good looks. Nevertheless, his desire is only for Ju-yeon, as he finds reasons for Sae-yan to contact her. He picks up the phone and is able to have a conversation with Ju-yeon at last. She claims that Sae-yan is more caring than she is, so he is well taken care of. We see her outside his apartment, hanging up and reminiscing about their fond memories.
She arrives just in time as Shin appears at her residence searching for her. Mrs. Kyung is amazed as he opts to hold off for Ju-yeon arrival in order to give her a surprise. She gets the fancy china out, but her grand-nephew, Seung-hyun, reveals the gossip about Shin. Mrs. Kyung hands over her deceased husband’s clothes to him with the agreement that he will wash them before giving them back.
While spending time with Seung-hyun, he is curious to learn more about his beautiful aunt, but Seung-hyun confuses him with thinking he is asking about Sae-yan. They argue while Shin asserts that Ju-yeon is more beautiful. He also stumbles upon Gun’s journal and confiscates it.
At Gun’s place, Sae-yan attempts to create grappa, an Italian elixir that calls for a spoonful of brandy. She is unsatisfied with the amount and continues pouring and tasting until she completes 2 bottles of brandy. When she arrives with the mixture for Gun, she is intoxicated and the solution turns out to be simply brandy. Gun finds it amusing to end up caring for her after she falls asleep. He provides her with hangover medication and pinky-swears to search for her father while she weeps for him.
Somewhere else, Ju-yeon strolls around the town and encounters one of her clients. He observes her appearing sad and concludes that she is experiencing heartbreak. Even negative recollections of the loved one turn into treasured memories due to this illness.
On her way back, she comes across Shin engaged in a game of cards with Mrs. Kyung. Furious, she pulls him aside and explains that she has been giving him the cold shoulder for a specific purpose. She thinks he kissed her for Gun’s benefit, but he affirms he is attracted to her. She is sorry for giving him false hopes but she does not have romantic feelings for him. He believes that she is acting unkindly towards him because of Gun.
She attempts to remove him since reasoning proves ineffective. At that instant, their conversation is abruptly halted by Gun, who is unwell, carrying Sae-yan in a drunken state on his back because she wants to visit Seung-hyun. Ju-yeon worries about Sae-yan while Gun is upset that she is not acknowledging him at all. Seizing the chance, Shin expresses gratitude to Ju-yeon for the wonderful evening and assures her that he will bring back her father’s clothes.
Gun remains unfazed and suggests a tennis match with Shin, pointing out Shin’s tendency to constantly stare at his belongings. While playing, Gun performs well, but Shin is the one to score the initial point. Gun suddenly inquires about Shin’s wristband, revealing that it is the same band that came off when Shin saved Gun at the bridge.
Shin is taken aback when he discovers that Gun has recollected some of the memories from that night. The observer from the bridge gazes at them in the distance. Following the game, Shin sets fire to Gun’s journal; however, the observer manages to snatch it away.
When it comes to Sae-yan, she talks incoherently about Gun while remembering that he first wanted to evict her. However, at the conclusion of the day, she is convinced that they have formed a friendship. Ju-yeon appears sorrowful and unintentionally scalds her finger while preparing food.
The following day at the Athlete’s Village, Shin and Sae-yan argue as they usually do, with her stating that he is not Ju-yeon’s preferred type and should not consider dating her. Guk-bong is smitten with her, but Shin is preoccupied when he receives a message from the witness, requesting a meeting.
Shin hurries to the place as Hong instructs his men to trail him. A strange man arrives and is grabbed by the bodyguards, only to be revealed as a fan. The real observer is outside and takes off. Shin sees him and begins to pursue him, but he gets hit by a car, injuring his knee.
In the meantime, Gun visits the police station to inspect the report of his crash. The police officer continues to talk about how Shin was such a great brother that he didn’t even pause to remove his shoes before leaping after Gun. Gun is puzzled because he can only remember Shin choking him before they were both in the water.
In the final scene of Episode 12 of Bad-Memory Eraser, Gun goes to the bridge and gets lucky when he comes across a truck that had been parked close by. While downloading the dashcam footage, he is interrupted by Guk-bong, who announces that Shin is nowhere to be found. As Gun searches for Shin, Ju-yeon freaks out when Seung-hyun reveals that Shin has stolen Gun’s diary.
Overall, Episode 12 does a fantastic job of weaving together emotional revelations with heightened suspense, setting the stage. This episode skillfully blends emotional depth, romantic tension, and mystery, drawing viewers further into the tangled relationships and unresolved secrets of the characters.