I loooooooooooove this! The central flashback would be perfectly sweet by itself but the framing gives it a depth and sadness that hit me so deeply without even seeing what happened. I wondered if the extras would spend more time on the how and the why but I was pleasantly surprised to see small snippets, arranged like scattered memories and dreams. Ending back in the present, with Mayu's expression turning into something more peaceful, is such a good expansion of the base story, again without letting you in on the details. Really great stuff.