The fact of it was, Ishigami had planned on devoting his life to mathematics. After he got his master’s, he had planned to stay at the university, just like Yukawa, earning his doctorate. Making his mark on the world.

That hadn’t happened, because he had to look after his parents. Both were getting on in years and were in ill health. There was no way he could have made ends meet for all of them with the kind of part-time job he could have held while attending classes. Instead, he had looked around for steadier employment.

Just after his graduation, one of his professors had told him that a newly established university was looking for a teaching assistant. It was within commuting distance of his home, and it would allow him to continue his research, so he’d decided to check it out. It was a decision that quickly turned his life upside down.

He found it impossible to carry on with his own work at the new school. Most of the professors there were consumed with vying for power and protecting their positions, and not one cared the least bit about nurturing young scholars or doing groundbreaking research. The research reports Ishigami slaved over ended up permanently lodged in a professor’s untended inbox. Worse still, the academic level of the students at the school was shockingly low. The time he spent teaching kids who couldn’t even grasp high school level mathematics had detracted enormously from his own research. On top of all this, the pay was depressingly low.

He had tried finding a job at another university, but it wasn’t easy. Universities that even had a mathematics department were few and far between. When they did have one, their budgets were meager, and they lacked the resources to hire assistants. Math research, unlike engineering, didn’t have major corporations waiting in line to sponsor it.

Ishigami had soon realized he had to make a change, and fast. He had decided to take his teaching credentials and make those his means of support. This had meant giving up on being a career mathematician.

He didn’t see any point in telling Yukawa all this, though. Most people who had been forced out of research had similar stories. Ishigami knew his was nothing special.

— The Devotion of Suspect X by Keigo Higashino (Detective Galileo) (Page 126 - 128)