Responses
I don’t think he’d be in his mid thirties. If he went to med school in Japan which is basically 6 years in college he would have been 24, plus residency = ~27, and as a coroner he would have had to go through 4 years of training in forensic pathology = 31, and as it appears that he spent some time being a coroner then I’d say he was around his mid thirties by the time this story began.

The mangaka didn't even have to do Hosaka Sensei like that. He looks like a whole 53. He should be like, mid thirties. Well, time does hit some people like a bus.