Mutual confession? Check (ch20).
Kiss? Probably check (ch20, just from the POV of the "stalkers"... it's too far away to be sure).
Sleeping together? Check (ch21, and even before).
Post-confession date? Check (ch21).
Together after a time skip of few years? Check (ch26).
"Adoptive daughter"? Check (ch26).
This may be a sort of Symphogear-lite but heck, it's also even gayer in the explicit sense. It's not like I'd be opposed to be more, but all in all the mangaka has the checklist pretty well covered.