Responses
The author said it in the last chapter xD http://www.mangago.zone/read-manga/bokura_no_mitsudomoe_sensou/mf/c005.5/pg-15/
I know, I didn't read that the first time. I have a habit of skipping things that are not directly part of the story. The second time I actually read it all and was like "HOW DID I MISS THAT!"
I'm normally pretty good at recognizing these details. ┗( T﹏T )┛
and only now realizing Kuni is Kuni from Bokura No Mitsudomoe and the "girlfriend" might be Daiki..... small world.