This was a series of children’s books about a centimeter thick and maybe 9″x 12″, a little larger than a standard sheet of paper. They were hardcover with maybe 30-50 pages of full color photographs and illustrated content. I read them in the early 90s in the United States, so they had to be published sometime before that. The inside format was like an Eyewitness book, with little vignettes scattered around the page which sometimes featured a cartoon child’s question for that topic. They were probably targeted at the 6-11 demographic.
This biggest stand-out feature is that even though they were in English, I believe the book was originally published in Japan (or an adjacent culture) because the illustrated characters took part in cultural or regional norms typical to Japan (sitting on stools in showers, catching horned dynastid beetles etc). The illustrations were very cute, a lot of the inanimate objects (teeth, tornadoes, pancreas) had little cartoon faces on them. I have attached a mock-up of how I remember the book cover and cartoon boy looked.
The title was something like “Tell Me Why” or “How It Works” or “Answer Me This”. The books had subtitles of the specific topic they focused on, like “Insects”. I think there was a question mark prominently featured on the cover of the books. There was also a cartoon boy with gray hair and blue shorts on the cover. I think each book featured different cartoon kids, but I’m not sure. The book would follow the kid as they asked questions about the world and received answers.
I had three or four different books in this series. Each book had a different color stripe/band at the top. I think the Insects one was green, the pink one was Weather, and the blue one was Human Body. Insects went through different types of insects, and it included real photographs along with illustrations. I remember an illustration of two stag beetles fighting each other, the artist gave the beetles cartoonishly big eyes. It talked about insect diets, and discussed defense mechanisms. It showed the life cycle of dragonflies, butterflies, praying mantises, bees, wasps, ants, pill bugs etc. There was big real life photo that showed the yellow blood a ladybug secrets when threatened.
The Human Body book talked about each organ and what it did, and how your body healed itself from bacterial infections and skin abrasions. It had a few pages that discussed the best way to take care of your body (exercise, healthy diet, etc). It described what a dentist visit might be like. It showed how a cavity is formed with a little illustration and what it might feel like to have one. I remember an illustration where there’s a frog, a raccoon, and a human child with their bellies face forward. This was to show that some animals, like frogs, did not have bellybuttons because they were not mammals like humans. There was a section about hygiene and I remember it advocated using qtips in your ears, and baby oil + qtips to clean your bellybutton! It had an illustration of a nude child and dad sitting on stools in the shower with dad holding a removable shower head helping the child wash off.
I don’t remember as much about the Weather book because I thought weather was boring haha. It probably discussed tornadoes, hurricanes and storms and why they form, and what to do if you’re caught in one.
And before anyone asks, no, it is not “The Big Book of Tell Me Why”, or the “Just Ask” picture book series (although I did own those and love them!).