“But the environment in Japan is such that if you go overseas to study, you have to be prepared to go your own route, find your own way,” he said.

Ryutaro Sakamoto, who paid his way through the University of Toronto and returned to Japan at age 30 with a business degree, found he was too old to apply through standard recruitment programs. He sent résumés to the likes of Panasonic and Sony, anyway, but never heard back. Eventually, the Japanese unit of the American insurance company Prudential was happy to put his bilingual skills to use.

“In Japan, taking the time to study overseas sets you back in the shukatsu race,” he said.

“Shukatsu” refers to the system in which Japanese companies typically hire the bulk of their workers straight from college and expect them to stay until retirement. Not getting a job upon graduation is seen as a potential career killer.

So competition is fierce. In the last three years, the percentage of new graduates in Japan who found work was the lowest since the government started collecting comparable data in 1996. As of Feb. 1, with two months left in the recruiting season, a fifth of students in their final year at college had yet to find jobs.

“Shukatsu is like Kabuki theater,” said Takayuki Matsumoto, an Osaka-based career consultant. “It’s difficult when you don’t fit the template.”

His advice to returnees: don’t be too assertive or ask too many questions.

Kenta Koga, one of only a handful of Japanese undergraduates to enter Yale in 2010, violated many unwritten rules last summer as an intern at a big Japanese advertising agency in Tokyo. On client rounds with his boss, who was advising on trends in technology or social media, Mr. Koga, a computer science major, felt the urge to speak up.

“Some of what they were discussing was old or plain wrong,” he said. But he was careful to steep his language in the appropriate honorifics reserved for elders. “I’m terribly sorry to interrupt,” he said he would murmur. “My deepest apologies if you already knew this.”