I didn't notice it on my first readthrough, but those faces in the last panel look rather smug. You'd think they'd known what they did.
Whats with Mami x BitingHerHeadOffWitch?
For the completion of pairings.
(And this is the very first time I see someone call Charlotte like that XD)
I like Mami x OL, but it seems hardly anyone else ever did(sadly, I got a taste from the one doujinshi that featured it and haven't been able to forget it). But since I haven't seen any MamiNagi that doesn't come off as sisterly, it seems like just the solution to slot them both in and get a happy family(assuming Nagisa doesn't mistake Mami for cheese again).