Delving into sordid and ruthless lives at the bottom of Japan Inc.'s social ladder, this whirlwind odyssey in search of Japan's current under-25 generation is a mixed bag. Undoubtedly, freelance journalist Greenfeld has unearthed some fabulously riveting material. Take, for example, his chapter on Choco Bon Bon and Emi, a pair of porn stars brought together by a wily entrepreneur called Shoji Onizawa. Choco is one of Japan's top male porn celebrities, named for his chocolate-hued testicles. We see him smoking shabu, or crystal meth, in a hotel room while Onizawa frantically tries to find exactly the right female lead -- an innocent who will be penetrated anally for the first time on film. The result is hilarious and grim. The film gets made, Onizawa makes his buck, and Emi, having been paid several million yen and a diamond ring, joins the ranks of the porn elite. Several of the chapters inevitably deal with the Yakuza (organized crime), and with the bosozuku, or motorcycle gangs. One chapter -- an enthralling portrait of working-class delinquency, ambition, and violence -- portrays Tats, a chimpara, or little prick, the lowest rank in the gangster hierarchy. Elsewhere, Greenfeld deals with such topics as hostessu (foreign bar hostesses), students at the elite Tokyo University housed in Third World--level barracks, the youth drug culture, right-wing militants, and Tokyo call girls. Overall, it's a tense and spicy read, sprinkled with delicious details and gossip. But Greenfield tries to be both hard-bitten and hip, with sometimes numbing attention to modish detail, and occasionally his tale is dragged down by heavy-handed writing. Both this book and the Japanese kids it so carefully describes bring to mind Dali's comment to a youthful painter: ""Don't try so hard to be contemporary. Alas for you, it's the one thing you'll be whether you like it or not.