No penetration when you have done practically everything else feels so cheap. Just say it happened off screen. Dammit author.
If this is not a shounen then MC would fuxk Nano daily already
I dunno about the other girls but from what we knew, he and Nano kissed and cuddled for hours in chapter 2, it would be weirder if they didn't have seg ( Not just Le populaire's effect, even Nyoru's liquid have aphrodisiac effect too ), I guess this is the power of weekly shounen magazine. No seg for you
Vol 1 extra mentioned that Nano got hooked to Nyoru's massage too, meaning MC made her wet daily ( look for the massage reference in chapter 1 ).
With other girls, MC and them is just at lucky pervert moments level but with Nano they are at "the universe need to use power to stop them from having seg" level.