As can be seen in this photo from a recent night eating with coworkers, it is not uncommon to have fried fish bones be served as part of a tempura set. In fact, fried eel bones are something of a special item. The bones become brittle and crispy when fried and the addition of a little salt makes them quite good.
However, despite eating many small fish whole and frying the bones of larger fish, the traditional Japanese diet does not contain adequate amounts of calcium, which is why the Japan Dairy Association is promoting the combination of dairy with the traditional Japanese diet in a program called New Washoku, where "nyu" or "new" can be written as dairy in Japanese and "washoku" means Japanese cuisine.
てんぷら 乳和食