There is an episode of Detective Conan where Conan and Heiji are working on a case in a villa.

141 The incident in the secret room on the eve of the wedding (Part 1)

142 The incident in the secret room on the eve of the wedding (Part 2)

Is this it?

This episode was the one that deeply impressed me when I was a child in the Mandarin version of Conan. Heiji was so handsome.

However, Conan was not hanging from the railing. Later, Conan accidentally fell down. Fortunately, someone caught him. That is, the gif below

I cut this gif because I like Heiji and this episode. It is very classic