I think you'd like "Unblossomed" manhwa. It also deals with a historical conflict. (though calling it a "war story" would be a bit misleading. It's more about Japanese colonial rule in Korea.) One of the mc’s Korean, while the other is Japanese.
But don't worry.. It doesn't romanticize any of it. Story handles the subject matter realistically and thoughtfully. Tbh It's genuinely peak and must read.

ngl i thougth this would end in tragedy
usually i don't like stories with war and love, they tend to be romanticized af without any scrutiny, but i guess the author did a good job portraying the hatred between nations with such few chapters