Comics for boys are called "shonen", and they normally include large doses of action and adventure. Warriors, fighting competitions, fantastic worlds, and mechanical wonders are common. There is even a sub-genre for gigantic robots called "mechas".
Focusing on an adult masculine audience, we have the comics called "seinen", with more elaborate arguments.
An finally, for children we have comics called "kodomo", with children stories and clean and clear lines. The characters and shapes are kind and round.