This is only the subtitle file.
The subtitle contains timing fixes for the released Blu-Ray version.
The subtitle uses the Arial Rounded MT Bold font, which may not be included with all OS, so the font has been added to the upload as well.
The movie has parts in Thai, so it’s possible without a compatible font, the parts would be unreadable. (There are still translation for them, so you can read those)
Bokura no Nanokakan Sensou’s official website: http://7dayswar.jp