There are some beautiful 80s-90s steel birdgestones or miyatas for example moving around that are build for racing but are like riding silk in the road, if i was in japan probably i would look for something like that out there. Aluminum rides are pretty stiff if you don't know. I would go with an old good steel racing japanese frame since you are there. Japanese people loves italian stuff too, wonder if yo ucan find a pinarello or a bianchi out there also.