Lotta flaws in this production but some good parts too.
The script sounds like a draft that needs a lot of work. In the right hands the anime might have been a new franchise series, but (I didn't read the anime) I suspect a lot of background material was left out. Some expansion on the why of the characters' motivations and background details would have helped. Given the wide variety of creative inputs it's surprising it worked as well as it did (not very well at all). The Korean and American actresses went on to active careers so they did what they could with the material. The movie was too short (1.5 hours) and even that was padded with excessive chopping and slashing scenes as if someone thought that would distract from the wooden acting and dialogue.
Once the big reveal happens I was curious to see more of the Saya character and what she would to do going forward. This movie should have been the set - up for a great series revolving around Saya.