Herbivore: an organism which gets its food energy from plant tissue.
Good start. According to CNN, a Japanese columnist is very concerned that a subset (possibly a generation) of young Japanese men is going soft. Maki Fukasawa applied the term "herbivore" to men who are not interested in typical manly pursuits (money, sex, kendo, rock gardening et cetera).
In the past one hundred years, the Land of the Rising Sun has gone through a myriad of identity shifts. They've gone from agrarian to industrial, from aggressively expansive to sternly pacifist, from fiercely isolated to a great cog in the global economy and, lastly, from exclusively male-dominated (to the point of misogyny) to… something else.
Maki Fukasawa (a woman, FYI) chose the term "herbivore" not to describe these chaps as graceful leaf-eaters (Or water-dwelling mammals. Where did you get that preposterous hypothesis? Did Steve tell you that?) but because the Japanese for sexual congress roughly translates to "relationship in flesh," which these blokes are not down with. Read: Japanese Women Buy Male Attention
In addition to avoiding double-backed beasts, these gentle creatures are prone to enjoying a manorexic physique and live under the assumption that men and women can be friends without an underlying need to consort (I'd buy that for a dollar*). The "Herbivore" revolution sort of combines the least Yang-y aspects of the Emo scene, metrosexuality, skinny jeans and the asexuality movement (of which I'm skeptical that there are more than five members who aren't just really bad at getting tail).
Maki Fukasawa (a woman) claims that the rise of the "herbivores" is actually a return to a kinder, gentler culture, rather than a rejection of time-honored chauvinism. While I agree that the stereotype of the sex-obsessed company man is probably overblown, the culture (and the region) does have a history of being OK with separating sex and relationships (not just adorable geishas but whores too).