The 12th episode, aired on the 27th, portrays Jin Seo Won (Cha Eun Woo) struggling to revive the memories of Han Hae Na (Park Gyu Young), who has forgotten all about him.
Heartbroken for Hae Na, who has paid the price of a curse, Seo Won tries everything to help her remember him. From wiping the dust off her desk as she once did for him to gifting her favorite sweet cakes, he stays constantly by her side. However, Bo Kyum (Lee Hyun Woo) captures Hae Na’s attention, sparking jealousy in Seo Won. Despite Seo Won’s warnings, Bo Kyum continues to provoke him, leading to a physical confrontation. Hae Na intervenes, only to push Seo Won away to defuse the situation.
The episode continues with Bo Kyum’s revenge surrounding the death of Cho Young (Kim Yi Kyung) in their past life. Having taken away everything that’s precious from Seo Won and Hae Na, Bo Kyum asks Hae Na out, leading to rumors of them dating in school.
Meanwhile, Seo Won, fighting a lonely battle, discovers that Min Ji Ah (Kim Yi Kyung in present life) hasn’t lost her memories. Suspicious of Bo Kyum’s actions to separate Seo Won and Hae Na, she uses the vice-principal (Yoo Seung-mok) to find mountain god Bo Kyum’s mountain. There, Ji Ah uncovers Cho Young’s past and pieces together fragments of her previous life’s memories.
During this time, Hae Na, unaware of the situation, heads to Seo Won’s house, where Yul is. Surprised by her sudden visit, Seo Won cannot hide his astonishment. Hae Na, feeling a sense of familiarity in a new place she’s never supposed to have visited, confesses, “This is my first time here, right? It feels like I’ve been here before. My head and heart are saying different things. I don’t understand my feelings these days.” To which Seo Won responds, “Shall I tell you?” and approaches her for a tender kiss.