Going from 7 day to 14 day adult regular pass, the price goes up by 16800 yen. If you take the tohoku shinkansen to Utsunomiya, Tochigi, the walk-up ticket price is less than 5000 yen. You would incur about 10,000 yen for the round trip, plus the 3000 yen for the N'EX to the Airport, you are at 3800 yen from breaking even.