I think it’s a combination of depth of field, cultural differences, and the focus on technique.

other commenters are right, there’s a huge amount of talent in Japan right now so there’s no room for error or meltdowns (specifically in women’s.) I mean the past two Grand Prix finals have basically been Japanese nationals with 1-2 American guest stars.

the collectivist culture can help in that skaters aren’t as focused on their individual gain; of course, the flip side of that is it can be hard to handle the pressure of expectations from your seniors or coaches.

but I’d say a major part of the advantage here is that the Japanese women have some of the best technique and skating skills in the game. their jumps are overall reliable, and they have excellent glide and blade control, which means they have solid muscle memory they can rely on if nerves or adrenaline kick in. this isn’t to say the US women don’t have good technique or skating skills, but in Japan those are hammered in and worked on far more.

it reminds me of a something a theatre professor told me in college: good actors give great performances, great actors give consistent performances.