Okay, uh, here I go with the explanation again.
Valkyria NEAV saga is actually one of four manga shorts by Takeuchi Takashi, one of Type Moon’s founders. The other three have been translated before AFAIK, but only half of NEAV saga was translated. That half, you can read here.
I lack a proper piece of art, since Valkyria is pre-pixiv/pre-danbooru/pre-y2k, but whatever.
p.s. I’m not sure how much Nasu had to do with this but Takeuchi probably draws a fair deal of inspiration from his stories to help author Valkyria.