Let me guess.
They'll hang out together, but suddenly Haruki can't come because Oni-chan won't allow it. So he's left with his two friends while crossdressing.
So when did this great war happen?
the movie guy said the movies comes from 1000 years ago. Here the "1000 years" is also mention.
but the museum guy is human and it's still fine when he's young so the great war is only decades ago.
Did her father died because her mother suck out too much life force or something?
she did said "don't choose someone who is about to die soon" in chapter 1