Although it seems like it could take place at some point of the show, it doesn't fit anywhere and isn't meant to. Like I said in another topic:
Kiva's movie isn't in continuity at all.
It aired between episodes 27 and 28. However, considering the equipment used in the movie, it should be watched at some point between episodes 24 and 27. On the other hand, the characterization is closer to right after episode 31. It's doesn't really fit anywhere though, because it's not meant to be part of the show.
It is kind of odd though how there isn't any kind of really different setting or obvious alternate ending style here, unlike the other Heisei movies which aren't in continuity. It just tweaks and mixes a few elements of the show's continuity for no reason, similar to some Sentai crossover movies.