That evening, the worker went home and collapsed in his living room. He felt like he couldn’t go to work anymore. The next day, his wife took him to the hospital, where he was diagnosed with depression. He was allowed to take a hiatus from his job for a few months. After graduating with a degree from a prestigious state-run university, he couldn’t believe what was happening to him.

The worker was one of a few patients in similar situations introduced to me by Takahiro Kato, a neuropsychiatry professor at Kyushu University in Japan. (Kato requested anonymity for the patients to maintain their privacy and protect them from repercussions at work.) Kato believes that these patients’ distress is an example of an emerging condition that he refers to as “modern-type depression.” At its heart, the condition is a struggle by some workers to learn how to assert themselves in a social context where they have little practice. And its reach might extend far beyond Japan.

Aside from a few researchers, most mental-health professionals in Japan don’t use the term modern-type depression. It isn’t a clinical diagnosis, and despite its “modern” tag, characteristics of the condition likely have always existed alongside other forms of depression. The term first gained prominence in the 1990s, when Japanese media seized on it to portray young workers who took time off from work for mental-health reasons as immature and lazy.

While the term still carries stigma, Kato believes it’s useful to examine as an emerging cultural phenomenon. In the West, depression is often seen as a disease of sadness that is highly personal. But in Japan, it has long been considered a disease of fatigue caused by overwork. The traditional depressed patient has been a “yes man,” someone who always acquiesces to extra tasks at the expense of his social life and health. What makes modern-type depression different, according to Kato, is that patients have the desire to stand up for their personal rights, but instead of communicating clearly, they become withdrawn and defiant.

Clinically, this type of behavior first started to appear with some frequency in the work of Shin Tarumi, a colleague in Kato’s department at Kyushu University. In the early 2000s, Tarumi noticed that some of his younger depression patients, particularly those born after 1970, had an entirely different personality profile than traditional depression patients. They didn’t try to maintain harmony at the expense of themselves, and they had less loyalty to social structures. Instead, they avoided responsibility. They tended to fault others for their unhappiness.

Several years after Tarumi died, Kato took over the line of research based on his own clinical observations. There are no definitive statistics on the prevalence of this type of patient. Patients exhibiting these characteristics tend to be middle class. Most are men, because men are more likely to seek professional help in Japan. There’s no connection to a particular type of job, because the issues patients face are mostly interpersonal. What they do share are similar personality traits and social conditions.