Tom Baker — not the actor who played the fourth Doctor Who, but a writer who regularly covers manga for the Daily Yomiuri in Japan— recently had a conversation with Aya Kanno, the creator of the manga Otomen, about how to draw boys for girls' manga. Most of the fourth volume takes place at the beach, and Kanno and her assistants spent a lot of time agonizing about whether to include nipples and sharply cut abs.
In the end, none of that stuff made it into the finished drawings; the boys are almost detail-free. To explain this, Baker recalled a conversation with Roland Kelts, author of Japanamerica:
A crucial element of [Japanese pop culture] style is minimalism, Kelts said. He described how Eiko Tanaka, founder of anime company Studio4C, made this point to him… “She very quickly drew a circle with these actually quite brilliant, exquisite points in it, in two or three strokes of the pen. And she said: ‘Look. What is that?’”
Despite its extreme simplicity, Kelts recognized the drawing as a cat. He said Tanaka then told him: “You can look at this cat, and imagine so much, see so much of the cat – your cat – because I haven’t filled everything in, because I haven’t identified the details of the cat.”
"Applying these ideas to 'Otomen,'" Baker says, "the blank space within a character’s physical outline allows each teenage girl reader to fill in whatever boy-body details are yummiest to her."
Obviously this isn't unique to manga — Scott McCloud makes a similar point with regard to cartoon faces in Understanding Comics — but it's interesting to see it being applied in a real situation. Not all shoujo manga is as simple as Otomen (which is about a very feminine boy, another reason for a lack of pecs and body hair), but the complexity is usually not so much in the drawings as the way the comic is put together. Some creators, such as Arina Tanemura, crowd the page with panels and crowd the panels with an explosion of different screentones — not just dots, but flowers and stars — but their characters usually remain straightforward. For someone accustomed to manga, Western comics that go the opposite way, with a lot of facial detail, can be quite hard to read (at least that has been my experience).