WMG / Sailor Moon: Another Story

Professor Tomoe and the Ayakashi Sisters died because their fates were changed by the anime and the game reset that.
Some force reached out and changed their fates to differ in the anime. The general theme of the game is that one has to accept the past. In order to stop Apsu, all changes had to be reset.
http://tvtropes.org/pmwiki/pmwiki.php/WMG/SailorMoonAnotherStory