The male clothing never becomes see through Because, Science? You see it’s to help people with research (who could possibly research to this is beyond me though)
@Someoneosm possibly... it's clear that there is some kind of relationship between Akatsuki and sensei, but whether that's sexual or not is unknown. Considering that sensei is not shutting down the MC's advances and seems to be genuinely interested in him while at the same time not going "all in" on him either, I'm thinking probably not a sexual relationship between her and Akatsuki. It will be interesting to see how this progresses.
@GoldenWolf
I think it might actually be sexual: we know they have some kind of relationship, they have each others contacts and are using them, even to talk about our MC, but we don't see them interacting much at school: someone in that kind of relationship would try to be subtle in contrast to the MC; so we only know about their relationship because of very specific things a third party wouldn't know. We know he isn't interested in the other girl that likes him and that his research for the club is on female body. Her willingness to do the perverted stuff with the MC, might hint at her doing it before(or more explicit things) as well.
I agree that it doesn't seem he'll do anything with sensei, but I doubt he'll achieve anything with Akari either, he is very blunt about not getting aroused by her what so ever and she'll need to finally accept he is an older women lover. Wasn't senpai interested in her?
@Samhill I didn't wanna dwell on it too much, but I was a bit confused by that sentence and had trouble translating it. As a non-native still learning the language, this happens sometimes.
The sentence being 時間は干後以降9時まで, which very roughly translates into something like "The time/timeframe is thereafter until 9 (PM)" although I'm not exactly sure what 干 means in that context, and whether she's referring to the timeframe of the date or his thinking time. In hindsight, she might have been referring to the date.