So how much is... (Spoilers)

Koustubh said:
the final physical age gap between both? 

Anzu waits 8 years for him so she is 25. Kaoru's wish of wanting to see his sister is granted, so surely even his lifespan must be reduced, (I say this because of the starting dialogue in the movie: "Do you know about the tunnel that grants you whatever you want? What the heck? When you walk through the gate in it, you'll come across what you want. But you'll age 100 years in return")

Then, both of them spend time equivalent of 5 years until Kaoru again wakes up. Overall, they are mentally 30 years old, but how old are they physically? Anzu probably will still be 25, but how about Kaoru? Also, similar to how Kaoru's wish was granted, even Anzu's wish of getting back her manga pages was granted, so wouldn't she age as well from that? 

Py687 said:
@ktg You're splitting hairs. If it pleases you then call it a "cost" instead of "penalty." Either way it's obvious what nocivo meant.