Shinichi: Don't worry- it doesn't make much sense to me either.
Miyuki demands Aoi show her proof that the world is a game, to which Aoi responds by... trying to take off her clothes. Her reasoning? If she's naked, a mosaic will appear to censor her. Even funnier in the localisation, which is left having to lampshade how that doesn't factor into the ENG version.
During the long, unskippable scene in the endgame where Miyuki masturbates in front of you, Miyuki herself lampshades this:
Miyuki: You know, you're lucky. In the Japanese version, there'd be a mosaic in the way.
One day Yuutarou discovers a mysterious pair of panties lying discarded at the front door of his house. Come the next day, at lunch time, Yuutarou seems strangely perturbed by something note For context, at first he is worried they might be his mom's, but then he finds out they belong to his younger brother...