So, looking only at the evidence that we have been provided with thus far, it does not look good for Shion. Say what you will about their respective levels of drunkenness, she was clearly drunk when Shion arrived. If you initiate sex with a person who is mentally and emotionally compromised, it’s technically rape. If they tell you to stop, and you continue on regardless, it’s even more so. Doesn’t matter if they eventually get into it, consent was still violated. Based on that, it seems pretty obvious, based on what we have seen, that Scion assaulted Nozomi while she was drunk and heartbroken, and either doesn’t realize how wrong it was or is simply trying to pretend it never happened. Either way, it’s a pretty scummy thing to do.
That being said, there are several things that aren’t adding up here. Shion’s reaction to being accused of betraying her friend is off, and there’s a notable gap between Shion arriving at the karaoke bar and the two of them having sex, as well as in between the two girls having sex in the karaoke bar and going to the hotel from chapter 1.
This whole story is honestly really intriguing (and pretty sexy to boot), and I’m looking forward to modifying my assessment as more of Nozomi’s memories return and more of the story comes to light.