Thread:J.Hideto Natsume/@comment-10733658-20150518154920/@comment-10733658-20150519080232

Juuzou reads the information about Kaneki off his student ID.

I don't know about Japanese IDs, but the ones I'm familiar with here in the US wouldn't have a person's full date of birth.

Unless the ID had Kaneki's DOB on it, Juuzou stating Kaneki is 19 just like him is a reasonable conclusion. He stole Kaneki's wallet in either late November or the first few days of December, so most people born the same year of them would already be 19. Kaneki just happens to have a birthday at the very end of the year, and it hadn't happened yet at that point.

That's all. I hope that makes sense to you now?