This informative image shows the process of change and refinement the various characters of crotch scrutiny anime Strike Witches have undergone through the evolution of the title.
The image starts with their real life base fighter aces, and then moves onto the original illustrations for the light novels and similar early works, after which the first anime iteration, the OVA, is shown. After this comes the tame manga, and finally the anime we know so well. There are some interesting changes evident.
In case you were wondering about the loli pantsu manga in the corner, you can read about their saga in detail here.