A small problem with the arranged marriage... (Major Spoilers)
The film takes place approximately 10 years after the end of World War II. Serizawa and Emiko are said to have been betrothed to one another since childhood. Since Serizawa was military age in WWII and Emiko was only 19, that means that Serizawa would have been a teenager and Emiko a child when they were first arranged to be married. Did that kind of thing really happen, in which someone had to wait for their wife to grow up, or was that a movie mistake?
Also, if Serizawa has been engaged since Emiko was a child, does this mean that Serizawa died a virgin? There's no implication of him ever having a fling with someone else and he certainly didn't get with Emiko in that fashion. It seems a real shame.