By: Kuwa-chan Set fifty years before the anime begins: it's the tournament won by Genkai, and Koenma attends, meeting by chance a certain Youko. And said Youko gives Koenma a gift he never got rid of.
All characters and settings property of Yoshihiro Togashi, Jump Comics, Studio Pierrot and whoever owns the video game rights. I have named a few characters that only appear in one flashback, however.