
I recently read the officially released and translated version and I think it's pretty clear now what the situtation of the doctor is.
He is a man (first name Akira), who crossdresses as a supposedly dead relative, likely his sister, as she looks super similar to him. From what I gathered, an aged relative (I assume the father) is either not aware or pretends not to know that it's Akira, and plays along as if Akira were that sister, even calling him by dead sisters name.
He's not trans and through context it's made clear he doesn't enjoy doing it, but forces himself. He overhears a talk between Shizuma and his collegues where Shizuma makes it clear that, if Minato were trans and prefer to be a women, he would 100% support his partner. (gosh, he's such a green flag, ugh)
Akira kinda realizes that for him the opposite is true, as he's forcing himself into that female role to appease his family member.
So far, it's unclear whether he will stop, come clean or sth else. Hope this clears things up for some! ╮( ̄▽ ̄)╭

I know I'm beating a dead horse, but it really feels like we peaked at volume 8, when Souichi actually initiated, kissed Morinaga out of his own free will and basically made it clear that he was into their sexy times (in his own tsuntsun way). But now it's kinda back to square 1.5, isn't it? At least that's how it feels like (づ ̄ ³ ̄)づ

Slight spoiler
From future chapters it looks like the doctor is male. Could it be that Shizuma knows this already, hence he doesn't realize how Minato considers the doctor a "threat"? To Minato, every pretty female around Shizuma is a huge problem, and if he thinks the doctor is a woman (which he does) of course he has a different take on the situation than Shizuma does. Not excusing Shizuma here, the whole "oh he's so jealous when he's cute" is honestly pretty random and kinda inappropriate.
Overall, I wish the doctor didn't play such a huge role, they just seem weirdly involved for no good reason outside of drama.

Gosh, I miss Shouhei and Itsuki so much, but I'm also kinda happy they have no drama. I'd probably die for a purely wholesome slice-of-life sequel with them though ╮( ̄▽ ̄)╭
Maybe Shouhei can introduce Itsuki to his friends (they seem cool) or some more shenanigans with the parents, who seem to love Itsuki!
I remember my teenager years when I was super into this story and I judge no one who still is into it, but am I the only one who feels very "ick" whenever Souichi hits/screams at Morinaga when he shows any signs of affection? Like, I'm not saying everyone should be lovey dovey 24/7, but it's sooo hard to root for them when their relationship still feels weirdly one-sided after over a dozen volumes.
I was recently trying to re-read some of the story and I was surprised by how uncomfortable most chapters made me, like I was reading a thriller about coercion, stockholm syndrome and the unhealthiest types of communication.
Hell, I still can't even say for sure if Souichi actually likes Morinaga in a general sense
┗( T﹏T )┛
Actually it really looks like that on the early chapters. When I first started this I stopped cuz I thought it was too coursive but now I think souichi has mature a lot, he's more open with his feelings and even though he still gets shy with morinaga's love shows he's willing to now and THAT is some progress. He's willing to wear a ring(though under the wrong ideas xD stupidnaga could just tell the true) he's willing to bring him home and still be relax with him, willing to support morinaga if he wants to present him to his parents. He's into this relationship now and wants to keep being with mori and that's a lot coming from Souichi
I started this when I was 15. I am now 30 and tbh, I don't want to be that friend that's too woke, but I half gave up on it cause not only did the story never advance, but it's reaaaally abusive and dismissive from both parties.
At least with other mangas that are still ongoing, such as Junjou Romantica, their characters developed their relationships in a mostly positive way.
Certainly their relationship started in the worse possible way(let's be honest mori graped Souichi and I ain't forgetting that but Souichi forgave and it wasn't in an unnatural way at least I think so) Souichi has taken his time to accept that what's happened and is happening between them can't be brush up as just a mistake. He stayed, I will never if I was on his situation and went through what he did but I think this is the kind of story this is. Their relationship is not just black or white they are both human and very selfish ones. Morinaga wanted to have souichis's love no matter what and Souichi couldn't completely cut off Mori so that's how this relationship started and has keep going.
I don't hate their relationship cuz morinaga is very devote and Souichi lenient still it's the kind of relationship I'll never wish for (but it's a nice manga and I've been following it since 2009 I think so imma stick to the end)