Difference between French bread and Japanese bread

One of the best known (if not the best known) breads in Japan is, in fact, very much like a brioche. Japanese Milk Bread contains butter and egg, it also contains a fair amount of sugar. The Japanese think of bread more like a sweet than a staple. Another sweet bread known in Japan is Maple Bread, it's even sweeter and really does taste like maple syrup.

If you are looking for something more like a French Baguette, Catija's advice in comments is excellent. The Japanese aren't big into sandwiches. The Vietnamese, however, have a huge French influence (whether they want it or not). The bread traditionally used for Banh Mi is a short baguette. If you ask for Banh Mi in Tokyo, someone will know just what you mean.

While I am not 100% sure what you are eating and looking for and am relatively new to bread making myself, I'm going to guess that what it comes down to is a matter of fat content in the bread.

What gets called "French Bread" (in the baguette sense) is usually a mixture of flour, water, salt, and yeast (similar to the recipe in The Bread Baker's Apprentice). It uses a pre-ferment (usually pâte fermentée, which is itself just flour, water, salt, and yeast) in combination with a mixture of flours to produce the final loaf.

Variations on this (e.g., pain de campagne) which maintain that characteristic texture still basically come down to a mixture of flours, walter, salt, and yeast. These are what can be characterized as lean breads: breads with very little (if any) fat added.

My guess is that most of the "chewy" breads you are encountering have a higher fat content. These are more like what in the US we'd call an "Italian" bread (which is frequently shaped in a similar manner to some french loaves, another example would be breads like Challah bread) all the way up to something like a brioche (which has a very high fat percentage). The fat adds some flavor and can provide a sort of softer mouth feel, which is what I suspect you are picking up on.

I think that different countries (including France and Japan) use flour with different ash and protein content.

eg. I cannot create the proper chewy/crunchy texture for baguettes, using the kind of flour commonly available in my own country. (And actually, I can't make very soft Japanese bread with our flour either).

French flour for baguettes use type 65 flour, which is high in ash and protein. It helps create the chewy, strong texture of the bread you are used to. I suspect the French type 65 flour is not commonly used or available in Japan. The characteristics of the standard flour used in different countries vary a lot, producing very different textures in baking products, even if they are called similar/same names (eg.'bread flour'). I think Japanese (and Asian) flour has a composition that can only produce very, very soft style breads and cakes.