I don't think that Big Eyes, Small Mouth (in anime), young girls
having relationships with adult men (also in anime), and 13 to 17
year old pop stars can be construed as evidence of lolicon in
Japan; I'm not saying that it isn't prevalent, to some degree,
in Japan, just that these things aren't good evidence for it.
Most anime/manga characters (in my experience) have small mouths
unless they're smiling, frowning, or talking loud. And while
women tend to have larger eyes in anime than men, I'm under the
impression that this is because "big eyes" = "cute" in the
Japanese culture. Thus, I don't think Big Eyes, Small Mouth is
any indication of lolicon.
And while there might be a lot of anime with adult men and younger
girls, I don't think that much of this is catering to, or
influenced by, any sort of lolicon. Most of the stories where
this occurs is written by women for girls. Many of the girls who
watch/read this anime/manga have fantasies about going out with
older men, and many of the writers had such fantasies when they
were girls themselves; it's a form of wish fulfillment. The only
shounen (boys) series I can think of with lolicon element is
Maze, where the barely-pubescent Mill is
in love with college age Maze. However, she's in love with both
male and female Maze (who switches genders depending on if it's
day or night), male Maze goes after anything female old enough to
have breasts (which Mill barely has), and... It's just so weird
in the sex/romance/gender departments that I don't know if it
should count.
Of course, in all anime/manga there's lots of unrequited
crushes by girls on older/adult men, but I don't see that as
having to do anything with lolicon; that's just life.
And the 13 to 17 year old girls who are Japanese pop stars...
Considering the popularity of the likes of Britney Spears among
young girls in the U.S., I wouldn't be surprised if their primary
audience was young girls. While men with a lolicon would
obviously be fans of these idol singers, I seriously doubt that
they're the driving force behind the phenomenon.
Examples of
shoujo (girl oriented) anime/manga which have
loliconesque relationships (and not just crushes by a young girl on
an adult man):
-
CardCaptor Sakura, the manga. 10 year old girl Rika gets
engaged to her homeroom teacher, Mr. Terada. (That's right,
engaged)
-
CLAMP Campus Detectives. 5th grader Takamura Suoh and 4th
grader Iyuujn Akira each have an, err, "girlfriend" who is in
kindergarten. Really.
-
In Magic Knight Rayearth, 14 year old Hikaru ends up with an
adult man.
-
In Fushigi Yuugi, 15 year old Miaka gets a virtual harem of
adult men who are interested in her, and she returns her love to
one of them (Tamahome).
-
In Sailor Moon, 14 year old Usagi (Serena) and college age
Mamoru (Darien) are a couple in the anime. (Mamoru is somewhere
from 18 to 20 years old; it's never laid down exactly how old he
is). In the manga, he's a high-school senior.