I don't think a movie from that perspective shows disrespect for the invaders. I look forward to seeing the movie from the US perspective. I likley won't see the other, even if it has sub-titles.
I have read a thing or two about General Kuribayashi, who was the Japanese commanding officer. Anything I have ever read about him suggests that telling the story from his perspective would be a tremendous compliment to the invaders. The way he commanded that battle suggests he certainly respected them.