In the former universe, you lose genetic continuity but may retain cultural continuity. Up to you whether that matters. To the Japanese, who adopt adults into the family to preserve the family business notion, one can speculate that they care about the cultural continuity more than the genetic continuity, but it's hard to tell.

Most online descriptions of Japanese people appear as caricatures, but from the few who I know who live in Japan, they are like any other human group: if some form of continuity or success is the only form accessible they will accept it.

It's the difference between Miami, a city whose population is more than fifty percent immigrants, and Detroit, a city whose population has declined more than fifty percent.