“I feel like I was an existentialist from the age of 5,” Yu, 44, said last month over dim sum near his home in Irvine. He’d suggested we meet at this restaurant in the Spectrum Center, a sprawling, pleasantly engineered outdoor mall that functions as Irvine’s de facto civic space. It’s the kind of place that, frankly, might serve as a setting for one of Yu’s stories, which are often about the uneasy feeling that something’s not quite right with the world. “Even as a kid,” he said, “I was always obsessed with these questions. Who am I? How did I get here? What am I doing in this place?”

Image Charles Yu’s novel “Interior Chinatown” comes out Jan. 28.

Despite these inclinations, he never believed he would be a writer. Instead, he went to law school at Columbia. It was there, while studying for the bar, that he picked up books of fiction that blew his mind: Saunders, A.M. Homes, Donald Barthelme — writers who grappled with those same questions in bracing ways.

So Yu started writing short stories of his own. He sent them out to literary journals. “I got hundreds of rejections,” he said. “I started posting them on a wall. But one in 50 stories would get published.” The stories were examinations of anxiety and heartbreak, usually framed by a high-concept conceit, such as the travails of a sad-sack superhero named Moisture Man. An agent read one and contacted him. Together they sold his first collection, “Third Class Superhero,” which was published in 2006.

The book was well-reviewed and sold decently. Still, in Yu’s mind, he wasn’t really a writer. He was a lawyer. “Not having an M.F.A., having a day job, there was always a feeling like I came in through the back door, or at least the side door,” he said. “Even to this day, it all feels a bit D.I.Y. It’s like I don’t play an instrument, I play a shoebox guitar I made in my garage.”