although the base idea is awesome but it's not really suitable for a 2h movie, a series has to be produced which could have the time for
2) digging into the fantasy world
3) making the imaginary world's rules clear (I didn't quite understand the 'fixer')
4) setting more and better plot twists (there was no interesting plot twist)
the movie didn't have time so just everyone had to trust each other immediately and to dive into the action and fight without preparing... it didn't have time to dig down into the mysteries of the two world (including the transfer technology) and there was no time to explain the present technology in the other Japan.
the war at the end could be a real fascinating strategic story which the viewer feels like a martial commander (like the one at the end of attack on titan season 3) but there was no time (it'll probably gonna take at least 3 episodes if a series is made)
>> I'm sure there can be a GREAT series out of the idea, I wish they make one someday
P.S : 'shin' was cute :)