You can look at this as they are drawings of fictional characters and they do not actually exist. Or, you can look at this as they're pushing over seventy, since World War II was kind of a really long time ago.
Furthermore, Unicorn can be seen as somehow underage cute young sister with all that personality and "innocent" dressing styles but in fact, take a better look at her body - she's grown woman, worthy Illustrious-class sister.
