Question on 90 day temporary visitor status

Just thinking a bout a quick vacation in Tokyo, I'm from USA so I go on a temporary 90 day visitor waiver. While in Tokyo I would like to depart Japan and fly to Seoul and return to Japan to continue my vacation for a few more days then depart from Narita to USA.

When I arrive at first in Tokyo, I will have a return ticket to the USA (about 14 days later). I will use a separate itinerary on a discount airline to make a round-trip from Seoul to Tokyo during my Japan trip.

From the immigration perspective do you think there would be any problem with this plan? Thanks in advance for any opinions.

I see no problem with your plan at all.

I did something similar a couple of years ago - main visit in Japan with a few days in S. Korea on a discount airline.

When I was leaving Seoul to return to Osaka the airline person asked if I had my return ticket from Japan to the US. Well, I didn't - it never occurred to me as I was going back to Japan for another couple of weeks. Anyway I ran around like a maniac to get a copy from the American Airlines office there - a real pain as I didn't have access to my email with the reservation code - anyway I got it and of course no one asked to see it....

Just a fyi to have it with you...

Thanks for the great replies.

Airlines often ask to see proof of return/onward travel because if you get rejected by Immigration, the airine is on the hook for your flight home.