Banana Fish is not based on real events. It's a fictional narrative that takes the reader/viewer into a made-up world with its own unique plot and characters.
Banana Fish is purely fictional. The plot, characters, and events were all imagined by the writer to create an engaging and unique narrative. There's no real-life inspiration behind it.
In 'banana fish short story', it focuses on Ash Lynx's journey. He is a character in a rather gritty world. The story may include his relationships with other characters, like Eiji. The plot is centered around the mystery of banana fish, which might be some sort of drug or something more sinister. Ash is constantly in danger as he tries to uncover what banana fish really is and how it affects people.
The Banana Fish anime doesn't fully encompass the entire manga. Certain elements might be missing or adapted differently. However, it does a decent job of presenting the main plot and key characters from the manga.