I'm pretty sure this is Kannazuki no Miko. Maybe they're early sketches...

comment #21044
Nopes. Those are sketches for an upcoming spinoff series. As can be seen above, Chikane and Himeko will be slightly redesigned, also they won't be Chikane and Himeko (but instead Kaon and Himiko) anymore, and supposedely won't be the main characters.

Also, a scan from manga:
post #74102