Instead of running 2 flights (one out of HND and one out of NRT) on some days, they are instead staggering them so only 1 flight runs each day. Which means some people originally booked on HND were moved to NRT. I wonder if the seat is broken and instead of getting bumped out of 1st class entirely, the other passenger chose to take the broken seat? (Although I am surprised that was an option - I've offered to sit in a broken J or F seat and was denied in the past on other airlines.)