May they live forever!!
In the chapter that introduces Shou, it is said that Katou is double Shou's age so Katou is 36. There really hasn't been much information about how much older Iwaki is to Katou but I've always thought it was somewhere between 4 to 8 years. In the chapter Love Tanker, it is said that Iwaki is way older than an actress in her 20s so I do think his age is in his early to mid- 40s. Hope that helps :-D
Thanks bro, now is more clear :)
I just looked it up and Iwaki is 5 years older than Katou
The very issue here is... how old are iwaki and katou? Are they forever young?
BTW I loved this manga, is one of my favourites yaoi ╮(￣▽￣)╭ (=・ω・=)