This manga is really good and the theme for it is different from the common isekai genre... The story is so down to earth and progress smoothly, though kind of rushing a little... All the details laid out in the story is easy to understand and line up logically...
The story progress is so interesting, the character development also satisfying though the ending is kind of heart breaking, NO... IT'S DEFINITELY A HEART BREAKING ENDING... Having read the manga, and watch the anime, I was hesitant to read this manga actually since I kind of predict it might be the stories of their hardship in developing a peaceful co-exist place for all race... I hope they will include extra on Yuuki and Zero lovey dovey life
Your in luck then! Yuki and Zero do have their moments but you gotta remember, Yuki will still always think about Kaname(and Zero). She loved both of them. But yeah, they have their lovey dovey moments.
Pressed that about all the Zeki we're getting, huh? Couldn't help but say "but but KANAME" (=・ω・=)