TOKYO—When the mother of a successful comedian was discovered to have collected welfare payments for many years, a heated debate broke out in Japan about who should support the growing ranks of the poor when both the government and families are struggling to make ends meet.

The image of Junichi Komoto apologizing in front of TV cameras for allowing his mother to stay on welfare captured national attention—for the complex emotions it stirred and for how long his head was bowed: 15 seconds.

The 37-year-old comedian was criticized by talk-show hosts and politicians for not providing sufficiently for his own mother despite his financial success. He once boasted paying ¥1.9 million (about $24,000) for a pair of watches and talked about his binge drinking at an exclusive Tokyo club.

But the story of Mrs. Komoto—a single mother who raised Mr. Komoto and his sister selling fish at a supermarket until she became ill—reminded people of the hardship so many Japanese now face as its once robust middle-class struggles. Mr. Komoto made just ¥100,000 a month as a young comedian when his mother first went on the dole in the late 1990s.

"I'd like to apologize deeply to the taxpayers who helped my mom for so long," Mr. Komoto said in nationally televised news conference last month. His case came to light after a magazine article about an unnamed comedian in April started a search.