A few days ago I got a review copy of The Manga Guide to Relativity (ISBN 1593272723). This is an English translation of a book first published in Japanese a couple years ago.
I assume the intended audience, at least for the original Japanese edition, is familiar with manga and wants to learn about relativity. I came from the opposite perspective, more familiar with relativity than manga, so I paid more attention to the background than the foreground. My experience was more like reading The Relativity Guide to Manga.
I expected The Manga Guide to Relativity to be something like The Cartoon Guide to Genetics. However, the former has much less scientific content than the latter. A fair amount of the relativity book is background story, and the substantial parts are repetitive. As I recall, the genetics book was much more dense with information, though presented humorously.
Some parents and teachers will buy The Manga Guide to Relativity to introduce children to science in an entertaining genre. These folks may be surprised to discover the sexual undertones in the book. Americans typically equate comics with children, but the book was originally written for a Japanese audience that does not have the same view.