Reunited Worlds

Sung Hae-sung (Yeo Jin-goo) is a senior high school student. On his birthday, his girlfriend Jung Jung-won (Jung Chae-yeon) prepares a surprise party for him at his house. To keep Hae-sung away while they set up, Jung-won asks him to go to their school and retrieve her wallet. There, he stumbles upon a shocking scene where a bully was found dead. While trying to get help, he is hit by a car and dies. Twelve years later, Hae-sung mysteriously wakes up on the roof of his school building, unchanged as a 19-year-old, while everyone he knew has aged. He reunites with Jung-won (Lee Yeon-hee), who is now a 31-year-old woman, and with the help of his friends, he sets out to uncover the truth behind his death and his sudden resurrection. As Hae-sung investigates, he discovers that after his death, he was accused of killing the bully. The real culprit was someone else, but Hae-sung was blamed, leaving his family and friends to suffer in the aftermath. Realizing that his resurrection has a purpose, Hae-sung dedicates his time to making things right. He helps his siblings, who struggled after his death, and supports his best friend, who was deeply affected by the false accusations against him. However, he soon learns that his return to the world is only temporary. He was given this second chance not to live again, but to resolve the past. As he brings the truth to light and ensures justice is served, his presence begins to fade. In a heartbreaking farewell, Hae-sung shares final moments with his loved ones, including Jung-won, with whom he shares a deep, unbreakable bond. Though they love each other, they must accept that they now belong in different worlds. With a peaceful heart, Hae-sung disappears, leaving behind a legacy of love, healing, and closure for those he cherished. == Cast ==

Main • Yeo Jin-goo as Sung Hae-sung (19-years-old) • Lee Yeon-hee as Jung Jung-won (31-years-old) • Jung Chae-yeon as young Jung-won • Ahn Jae-hyun as Cha Min-joon (34-years-old) Recurring Hae-sung and Jung-won's friends • Shin Soo-ho as Kil Moon-shik (31-years-old) • Kim Min-sang as young Moon-shik :Electronic Service Center employee. • Lee Si-eon as Shin Ho-bang (31-years-old) • Park Sung-joon as young Ho-bang :Police officer. • Kim Jin-woo as Cha Tae-hoon (31-years-old) • as young Tae-hoon :The chief executive of a department store. Cha Min-joon's younger half-brother. • Park Jin-joo as Hong Jin-joo (31-years-old) • Park Jin-soo as young Jin-joo :Roaming yoga instructor. Hae-sung's siblings • Yoon Sun-woo as Sung Young-joon (30-years-old) • as young Young-joon :Chest surgeon. Sung Hae-sung's younger step-brother. • Kim Ga-eun as Sung Young-in (26-years-old) • as young Young-in :Employee in a clothing department store. Sung Hae-sung's younger step-sister. • Kwak Dong-yeon as Sung Hae-chul (25-years-old) • Jeon Jin-seo as younger Hae-chul :Sung Gong-joo's father. Sung Hae-sung's real younger brother • Kim Hye-jun as Sung Soo-ji (19-years-old) • as young Soo-ji :High school senior. Sung Hae-sung's younger half-sister. Hae-sung's family • Kim Han-na as Sung Gong-joo (6-years-old) :Sung Hae-sung's niece. Sung Hae-chul's daughter. • Park Seung-tae as Kang Mal-yi (78-years-old) :Sung Hae-sung's grandmother. Extended • Park Yeong-gyu as Cha Kwon-pyo (65-years-old) :Cha Min-joon and Cha Tae-hoon's father. Cheongho High School Chairman. • Bang Eun-hee as Yoon Mi-na (55-years-old) :Cha Tae-hoon's mother. Cha Kwon Pyo's second wife. • Han So-hee as Lee Seo-won (27-years-old) :Sung Young-joon's girlfriend. Hospital Director's daughter. Fashion journalist. • Kyeon Mi-ri as Son Myung-ok (55-years-old) :Lee Seo-won's mother. • Kim Byung-se as Lee Gun-chul (58-years-old) :Lee Seo-won's father. Hospital director. • Ahn Gil-kang as Ahn Tae-bok • Lee Je-yeon as Yang Kyung-chul • Kim Hee-jung as Nam Yoo-min :Sung Gong-joo's biological mother • Min Joon-ho as Sous-chef (30-years-old) • Choi Sung-min as Dong-hyun • Ahn Sol-bin as Nam Soon-ji • Kim Young-woong as Moneylender • Bae Jin-woong as Moneylender • Jung Wook • Kim Dong-kyoon • Baek Ji-won as Landlord • Han Eun-seon • Oh Jung-tae as Accessory salesman • Park Hyun-sook as Cha Min-joon's maternal aunt • Kang Sung-min as Park Dong-seok / Jason Park Special appearances • Seo Yi-sook as Jung Jung-won's mother • Yoon Mi-ra as Lady Doh • Jeon Gook-hwan as Ha Do-kwon == Production ==

The series is the third collaboration between writer Lee Hee-myung and PD Baek Soo-chan, who worked on A Girl Who Sees Smells (2015) and Beautiful Gong Shim (2016). == Original soundtrack ==

Part 1 Part 2 Part 3 Part 4 Part 5 Part 6 Part 7 == Ratings ==

• In the table above, represent the lowest ratings and represent the highest ratings. • NR denotes that the drama did not rank in the top 20 daily programs on that date == References ==