^-- Because in 79AD a group of crazy zealot Jews had a mass suicide, so that made the stereotype thing. And a ton of religious people (not Jewish) killed themselves because Y2K didn't end the world, and they killed themselves at Armagenddon in Israel.
Suicide in Japan really isn't that widespread, and even when a Japanese person does it, it's usually because of a major failure in career or education, which is (even though there is no excuse) a better excuse than losing a girlfriend...
Oh, and there's a suicide club at my school, called the Living Death Crew (LDC), and about 8 of them have killed themselves for no reason but for fun over the past 10 years.