User blog comment:Nomimushi/Discussion: Shizuo's Age./@comment-33442125-20171110033405

I think the confusion lies in the fact Izaya and Shizuo's page have their ages labeled 24 for the Daily Life Arc when it was actually before.

There's a huge gap of time between the first and the second novel. So in the Saika arc, it is mentioned it is February, ten months after the initial first arc of the series. So Izaya and Shizuo are both 24 in those arcs onward. Izaya remains 24 until the end of volume 6 which covers the Dollars vs. Toramaru arc / Dollars & Blue Squares arc. At least, that's what it should be.

The anime didn't help at all with this. I checked the episode with Izaya in the hospital and the news segment listed his age as 24. But this is contradictory to the timeline in the novel. Or perhaps since he was hospitalized on his birthday they didn't count that he aged up once? I think that's a mishap.

Well, according to the timeline of the novels when Izaya is recovering in hospital to the end of the original series he is 25. In the sequal series SH and the Izaya Orihara spin off series are nearly two years. If we go off of the first two volumes of SH Izaya would be 26 and the Sunset novel takes place in summer so he is 27 there.

Does this make sense at all? Or clear up any confusion? At the very least I don't think "Daily Life Arc" should be listed for their ages of 24.