Hi… Other people have mentioned weirdness with Tokyo-related routes lately:
https://community.fly.io/t/ipv6-routes-eu-traffic-transatlantic/28204/4
(The forum unfortunately doesn’t have a specific tag dedicated to this topic, even though Anycast was the original raison d’être of Fly.io, 
.)
If you could post the mtr traces mentioned in those, that would probably help them diagnose this further…