Could I please have a little bit more detail on the circumstances around this?
(stuff like "is this a re-attempt", or "how far into the fight were you", etc.)
I've never experienced this, usually when either Kris or Susie's HP goes past 0, you get a game over screen.
If I can figure out what caused it, I can fix it, but with the given information, I genuinely have no idea how that happened.