Dreamland Japan tries to cover all aspects of manga from Horror to Mahjong, there's 5 pages on Maruo and a whole chapter on Tezuka.
If people buy it to read about their favourite manga then they'll probably be disappointed, but if you're interested in the history of manga, want to know more about the Japanese publications and the diversity of styles and themes out there then it's a good read. Here's the full content's list:
DREAMLAND JAPAN: WRITINGS ON MODERN MANGA