eat live prey whereas the Japanese are island-dwellers who eat not only raw fish but also sometimes live lobster. See here. In the twenty first century, when we read something incredible in a work of fiction, we will be able to confirm or disconfirm it by consulting a global computer network.
(ii) The Japanese fought against the Allies in World War II but later cooperated with Western Intelligence services in spying against the USSR. The Domain of Ythri fought against the Terran Empire in a border dispute but later cooperated with Imperial Intelligence against the Merseians.
I don't expect to find any comparisons more fanciful than these but will keep looking.