Indous mother protected Kagami from some kind of accident and died in the process (like saving her from truck-kun but getting hit herself). Kagami's mother obviously blames Kagami and Kagami blames herself by now too. There will be a fallout, Kagami tells Indou what happens and Indou forgives Kagami, telling her it's not her fault and both live happily together, either in the army or somewhere else after leaving