Maybe the mangaka is too embarrased to draw them detailed? There's sometimes I feel soooo awkward when I have to draw naked body in art class, I cannot calm down when I start to draw in some parts, girls body still ok coz Im a girl (still awkward though) but when I start man body I was like cannot finish the penis. In the end I ask the lecturer if I can draw the man wearing a boxer.
It's due at least in part to censorship laws in Japan. Putting little bars on body parts or showing a blank outline is one way that mangakas deal with legal restrictions. Another one is the famous "lightsaber cock" :P
I know it doesn't make a whole lot of sense, but until the laws are reformed, it's something we all have to work around. In a few cases, scanlation groups have the resources to de-censor stuff. Unfortunately, this is not very often.
can someone please explain sensorship to me? I sincerely do not understand. Why, the outline is there but it looks like someone cut it out and stole all the D's for themselves??? What is the point, you can tell what it is, its not fooling anyone. Also why is it only penis being censored? his freaking hole was gaping open!!! Do mangaka or their company or whatever really think that by turning a penis into a lightsaber you cant tell what's going on or what's what? kids arent stupid, graphic sex is graphic sex with or without a beautiful D, but I want a beautful drawn out penis. So does anyone actually know why censorship is the way it is? mostly just explain logic for this story? (sorry for really long pointless comment, luv'd the story)