I can't be saying shit, but when they show the age of chika it had a "physical age" and with the two semes it was just the age so i think chike just have the physical age of 16, because if u think that he was a doctor, he must actually have a least 28 years (sorry the if the english is bad) ╮(￣▽￣)╭
Chikas age in his previous world as a doctor was actually 40 as stated in the summary and is now in the body of his 16-17 year old self so uhhh yeahhh.. A-asian genes amiright? Haha
You don't have to worry lol, he's a doctor on earth, so he's most definitely not 16-17 since going to med school and becoming a resident would mean you're at least in your mid 20's lol.
I know their lifespans are different and whatever, BUT I CANT HELP IT. I can't get over the fact that's he's like in a 16 Year old body and they're in their 30's. Imma just chop it up to Asian youthful looks and pretend he's 18