This story was based on an episode that was not aired on TV and a script which was officially provided by Toei and was released in 2001 after Kamen Rider Kuuga's full televised run. The oneshot takes place in between Kamen Rider Kuuga's Episode 22 and Episode 23.

Original Web Manga

From xkazemg: Through music, they met each other; they knew they were soul mates to each other. But he was already engaged to the woman whom he sworn he would love for the rest of his life, and she a raising star in the music industry… eventually they parted their ways and decided not to see each other again. But 14 years later, and after the death of his wife, her life was about to change again, after his daughter showed up in her life…