DISPIRITED Akiko Oka has worked part time in an Osaka clothing shop since her store closed in 2002. She said she lamented Japan’s loss of vigor.Credit...Hiro Komae for The New York Times OSAKA, Japan � Like many members of Japan’s middle class, Masato Y. enjoyed a level of affluence two decades ago that was the envy of the world. Masato, a small-business owner, bought a $500,000 condominium, vacat