@lazunekko There's also the lotion page, where Ai-chan confuses lotion for lube and comments that it's such a hassle to use saliva... which can really only be interpreted one way. And the "I heard some noises that one time" comment is kinda outside of canon. However, we do have the "you're the one I love" comment too, so...
I guess it's possible that she hasn't had PnV but has done a couple other things with Onii-san. But nothing outright confirmed yet.
Best part for me was Maegami-chan marching to the shrine, her unfathomably intense desire for SENSEH'S BAHBEE making even the Tawawa-no-Kami tremble in terror and beg her for mercy.
@Wildstag: Wait, when did this "confused lotion for lube" happen?
Holy cow, I had to look it up, but a high yield dairy cow really does produce up to 12 metric tons of milk a year.
They can make 12,000 liters of milk over 10 months. Up to 60 liters in a single day.