➳ In which Lee Seunghee writes letters to her crush. Started : 12/08/2023 Ended : 21/09/2023 The Heartbreak series / The Letter Series : # Zhang Hao - Book 1 [ ] # Han Yujin - Book 2 [ ] # Sung Hanbin - Book 3 [✓]

➳ In which Seo Ryeon writes letters to her friend who knows her biggest secret. Started : 01/08/2023 Ended : 10/08/2023 The Heartbreak series / The Letter series : # Zhang Hao - Book 1 [ ] # Han Yujin - Book 2 [✓] # Sung Hanbin - Book 3 [ ]

➳ In which Kim Taehee writes letters to the one who broke her heart. Started : 31/07/2023 Ended : 04/08/2023 The Heartbreak series / The Letter Series : # Zhang Hao - Book 1 [✓] # Han Yujin - Book 2 [ ] # Sung Hanbin - Book 3 [ ]