Althea Creations

Published at the height of the '80s OVA boom, Movic's Creations series of books presented a no-nonsense look at the design materials used in the production of various OVAs. Each book consists of a single color page while the rest of the book is production settei (lineart that defines the characters, mecha, and settings of an anime). While you won't find screenshots or written material (aside from designer notes on the settei), the lineart included is generally much larger than you'd find in comparable books and the series covered more obscure OVAs. 

Althea Creations features settei from Good Morning Althea, a sci-fi OVA from 1987 that featured character designs by Kia Asamiya [Nadesico, Silent Mobiüs]. Inside you'll find lots of character lineart, mechanical designs, and details like cockpit layouts and background sketches. Most pages also include designer notes (in Japanese). There weren't many (if any!) other books published that covered this obscure OVA, so if you're a fan it's worth picking up.