It was posted recently on Anime News Network that a new Seikai series was announced in Japan. My guess is that the anime will be called Seikai no Senki III, though really we know nothing about the project other than that its been announced.
Yeah, it will be based on Morioka's Third Novel in the Senki Series, Seikai no Senki III. However, we don't know if it will be a TV series or One shot OVA. Also, this information came from a little cover advertisement that came with the recently released Seikai no Senki IV Novel.
I cant wait for it myself... i do hope its better than Banner II was.
I just didnt like how Banner II was done compared to the rest of the series.. it was good, dont get me wrong.. but it was not up to par with the first two