Case Closed (1996)

Season 14

Episode 39: Love Letter to Ran

Ran receives an anonymous "love" letter that has Conan worried. Ran isn't able to decide if she should go meet this person or not. Then Ran, Conan and Sonoko help a lady which then leads to saving a man's life. The man had once sent a love letter to this lady and thanked her for coming that day even though she had rejected him. From this Ran decides to go meet the person who sent the letter.