To access those transcripts, you must enslave Ms. Rack by any means possible, then change her into a bimbo. Attend her second secret class (floor ten note) while she's a bimbo, then change her to normal and speak to her in her classroom.
Then there's the Transcript List if you're not interested in the best teacher in the game being in her second best form (note: personal opinion, not to be taken seriously).
This transcript starts from that Ms. Rack talks to the Protagonist in her classroom after her class.
Ms. Rack's Plead
Ms. Rack: [Protagonist], can we talk for a minute?
Allow her to speak.
Protagonist: We can. What did you want to discuss?
Ms. Rack: I have a problem. It seems that while I was bimbofied, I may have... made some promises to a few students.
Protagonist: Sexual, I assume?
Ms. Rack: Yes. Letting me attend class while like that was not a good idea.
Protagonist: So, what do you want me to do about this then?
Ms. Rack: For one thing? No more bimboficiation. And... If possible, maybe you could make those students forget about my promises?
Help her completely.
Protagonist: Alright, I can agree not to let you go to school as a bimbo .
Ms. Rack: I said no bimbofication.
Protagonist: You did. But I am your owner. If I decide to bimbofy you, I will. You will be happy to hear that I am considering your concerns.
Ms. Rack: ...Yes. Thank you.
Protagonist: Now, what did you have in mind for the students you made promises to?
Ms. Rack: I've promised them one on one sessions. If you are here, you can make them forget all about it and send them on their way.
Protagonist: Sounds reasonable. Let me know when to be here, and I will.
Agree to not bimbofy her at school, but make her keep her promises.
Protagonist: Alright, I can agree not to let you go to school as a bimbo.
Ms. Rack: I said no bimbofication.
Protagonist: You did. But I am your owner. If I decide to bimbofy you, I will. You will be happy to hear that I am considering your concerns.
Ms. Rack: ...Yes. Thank you.
Protagonist: I will not have you go back on your word though.
Ms. Rack: It's not word! I was a bimbo when I made those promises!
Protagonist: You still made those promises, not me. You have to take responsibility for them yourself.
Ms. Rack: Responsibility? You made me that way. You are as responsible as I am.
Protagonist: True... So I will do my part and make sure you keep your word.
Ms. Rack: N-No, come on! Don't do that!
Protagonist: I order you to fulfil [sic] every promise you made as a bimbo. With a smile on your face.
Ms. Rack: I can't believe... Ah... Y-You can't... I... You're right. I have a duty to my students to keep my word.
Protagonist: Good girl. I'll leave you to your duties then.
Ms. Rack: Thank you, Master/Mistress. I will do my best.
Refuse completely.
(This presumably locks you out of the plotline).
Protagonist: No.
Ms. Rack: Wh-What??
Protagonist: I'm not going to stop playing with you however I like. I am also not going to help you get out of anything you get yourself into.
Ms. Rack: Please! I can't do this!
Protagonist: Oh, is that the problem now?
Ms. Rack: I... Don't think I like where this is going.
Protagonist: We are on the same page then. It's time to become a bimbo again.
Ms. Rack: N-Not now! Not at school!
Protagonist: Something wrong with that?
Ms. Rack: Of course there is! There are other... Ah... People here! I-If you make me dumb and horny again I'll...
Protagonist: Offer more promises?
Ms. Rack: Ah... Y-Yess...
Protagonist: That will be unfortunate, won't it.
Ms. Rack: Mmm... It... It will?
Protagonist: Will it? Or will it be fun?
Ms. Rack: Yah... It'd be like...
Ms. Rack (Bimbo): ...Lots of fun!
Protagonist: Good girl. Have fun.
Ms. Rack: Like, thanks! I'm totally gonna fuck some hot students today!
Ignore her.
(It goes without saying, this locks you out of the route).
Protagonist: I don't have time right now.
Ms. Rack: It is urgent.
Protagonist: And I said no. You will not speak of whatever it is to me again. That is an order.
Ms. Rack: I... Y-Yes. I understand.
The First Lesson
Ms. Rack: The first student should be here soon.
Protagonist: Alright. So, what did you promise them?
Female Student: Um... Excuse me?
Ms. Rack: She's here. Hello, come on in.
Female Student: Oh, I didn't know you had someone else here too.
Ms. Rack: Oh, yes. [Protagonist] is here for the same lesson. I thought it would save time to have the lessons at the same time.
(If the Protagonist is Dan)
Female Student: ...He... Wants to make his breasts bigger too?
Dan: Wait what??
[Ms. Rack lowers her voice to whisper to you.]
Ms. Rack: She won't remember I said that after you erase her memory, don't worry about it.
(If the Protagonist is Rosa)
Female Student: Oh. I... I guess that makes sense...
Rosa: That's what you promised??
[Ms. Rack lowers her voice to whisper to you.]
Ms. Rack: Yeah... It's embarrasing! Just make her forget, please.
(This line is next regardless)
Ms. Rack: I should lock the door so we won't be interrupted.
Female Student: So... I guess I'm not the only person who has trouble changing the way they look then, huh?
Protagonist: ...Yeah. Seems that way.
Female Student: That's sort of a relief.
Ms. Rack: There we go. [Protagonist], would you like to... Begin?
Use your power on the student.
Protagonist: I'm ready to begin.
Ms. Rack: Good. You have a spell that can change how others look. Use it on her so she can feel what it's like to be changed.
Female Student: Oh, okay. I'll try not to resist then.
Ms. Rack: Yes, that would be best.
Protagonist: Here goes...
Female Student: Ah... That feels... Ooh... Wait this... This is going... Ah! It's in my mind! This... This isn't transformation magic! M-Ms. Rack! Ah! S-Stop him/her! S/He's not c-casting the right sp-spell!
Ms. Rack: Sorry. It does feel good though, so don't worry.
Female Student: M-Ms. Rack?? Ah! I... Ahh... I can't hold out... M-Much...
Ms. Rack: Just give in. It's all you can do now.
Female Slave: Ah! Ahhh Yes! YES!!!
Protagonist: There. Your problem is solved.
Ms. Rack: You... Didn't tell her to forget anything yet.
Protagonist: That doesn't matter anymore. Does it, girl?
Female Slave: Ahhh... No... Nothing matters unless you command it to...
Protagonist: See?
Ms. Rack: That... Wasn't exactly what I had in mind.
Protagonist: You don't mind that, do you?
Ms. Rack: No. If you want to make slaves of each student, then you may.
Protagonist: Glad to have your approval, slave. Now lets go...
Make Ms. Rack teach the lesson.
Protagonist: Yes, I'm ready for you to teach us. Go ahead.
Ms. Rack: Ah... I meant...
Protagonist: I know what you meant. Lets start your breast expanding lesson.
Ms. Rack: Oh. Yes. So... So... You want to start with any physical boosting spell you have... You start to cast the spell... Then picture your body the way you want it to look and...
Ms. Rack (Bimbo): Let it become a part of what you are.
Protagonist: You look just like- Um, just like you did in class.
Ms. Rack: That's right. Go ahead and try it.
Female Student: Okay... My spell isn't great but... Hm... No... How about...
Female Student (now looking like Ms. Rack): L-Like this?
Ms. Rack: That's rihgt. You look very close to my normal form.
Female Student: Ah! Oh... I lost it...
Ms. Rack: It can be difficult to modify a spell and maintain it.
Female Student: I feel tired...
Ms. Rack: You used most of your stamina. That is why the spell dropped. It will get easier over time.
Female Student: Thank you, Ms. Rack. This... This is an embarrasing thing to ask for help with. Unil I saw you do that... Special lesson I didn't think I could even try asking.
Ms. Rack: It's my pleasure. Just keep practicing and you'll be able to maintain the kind of body you want all the time.
Female Student: Thanks!
Ms. Rack: I need to get ready for my next class, so I'll see you two later, okay?
Female Student: Okay. I'll keep practicing in the meantime. Thanks again for helping me.
The Second Lesson
Ms. Rack: She should be back soon...
Protagonist: ...The same girl?
Ms. Rack: Yes. She needed to learn how to make her breasts larger before I could give her... lessons...
Protagonist: What kind of lessons?
Ms. Rack: ...Titfucking lessons...
Protagonist: So, how can I help?
Ms. Rack: You will need to allow her to practice on you.
(If the Protagonist is Dan)
Dan: That doesn't sound too bad.
Ms. Rack: So, you'll do it?
(If the Protagonist is Rosa)
Rosa: Um... I don't have the parts for that?
Ms. Rack: I'll have to use my magic to give you the parts temporarily... If that is okay with you.
Agree to help.
Protagonist: Sounds good to me.
(If the Protagonist is Dan)
Ms. Rack: Thank you. She should-
(If the Protagonist is Rosa)
Ms. Rack: Thank you. Let me just use a bit of my magic... And... There. She should-
Female Student: Um, hello? Oh, I didn't know you would be here again.
Ms. Rack: Yes, s/he will be helping you practice.
Female Student: Oh, alright then. So... Where do we begin?
Ms. Rack: I'll lock the door first, you two should... Strip.
(If the Protagonist is Dan)
Ms. Rack: Then, you will need to wrap your breasts around... his cock...
(If the Protagonist is Rosa)
Ms. Rack: I've given Rosa a... A temporary cock. You will need to wrap your breasts around it...
(This line is next regardless)
Ms. Rack: After that, you... Um... What are you doing??
(CG: Student titfucking the Protagonist by leaning over his/her leg while Ms. Rack stares dumbfounded in the background)
Female Student: I'm putting my tits around his/her cock!
Protagonist: Ah... They're so soft!
Ms. Rack: What are you doing going over his/her leg like that? You're going to stretch or pull something!
Female Student: I don't know! It just... Feels like I should be facing this way.
Protagonist: It... It does feel like a good angle for... Viewing...
Ms. Rack: What are you two even... Nevermind. Just... Just apply pressure with your hands so it's tight around the... Cock. Okay?
Female Student: Mmhmm!
Ms. Rack: Then move them up and down, and try to keep it from slipping free.
Female Student: Ah! I'm trying my best!
Protagonist: Hah... It... Ah... It feels good... To me...
Female Student: I... I see the precum!
Ms. Rack: Good. Use it as... Lubricant.
Female Student: Y-Yes Ma'am! ...It looks so good... D-Do you think I could taste it when... You...
Ms. Rack: You should begin to tease the head with your mouth now, so yes. You will end up tasting it.
Female Student: Oh! Y-Yes, Ma'am!
[Following Ms. Rack's instructions, she begins to bob her head down to kiss and lick the head of your cock on each down stroke. Between the soft warm of her breasts and the teasting from her mouth you soon find yourself on the edge.]
Protagonist: I... I'm going to...
Ms. Rack: Quickly, put your lips around the tip and... Drink...
Female Student: Mmmhm!
Protagonist: Ahh! I... I came...!
Ms. Rack: Good. now you two get dressed.
Female Student: Thanks. I feel a lot more confident now.
Ms. Rack: ...You are welcome.
Female Student: See you later!
Ms. Rack: Well... That's done...
Protagonist: It seems odd for you to be this shy about sex. You don't have this problem any other time.
Ms. Rack: ...Normally, I wouldn't be. But... Every part of this reminds me of being a bimbo in front of everyone.
Protagonist: I see...
Ms. Rack: Context really does matter, you know.
Protagonist: Well, let me know when the next lesson is.
Ms. Rack: I will. Thank you.
A Promise to Reese
(If the Protagonist is Rosa and you used Boost on Reese after transforming him into a female or you promised to help him, this scene plays out).
Rosa: I have a friend who needs help then.
Ms. Rack: Help? As in, another lesson or...
Rosa: As in... He sort of... Had an incident? And doesn't have... Working parts?
Ms. Rack: That really sounds more like something for Dr. Tiff to look at.
Rosa: No, it's not an injury. It's more like... Um... He was... turned into a diluted sex change potion? Accidentally?
Ms. Rack: Potions don't work that way...
Rosa: I don't know, this one did!
(If you cast Boost on Reese)
Rosa: I made him a new body, but it's not... Functional down there.
(If you promised to help Reese)
Rosa: We've been trying to figure out a way to get him male again.
(This line is next regardless)
Rosa: Is that something you can do? Permanently, I mean?
Ms. Rack: Yes, it is.
Rosa: Good, I will bring him here then.
Ms. Rack: I will be here. And... It's nice to see you helping people.
Refuse to help.
Protagonist: Sorry, I don't think I can help with this one.
Ms. Rack: I... But...
Protagonist: That's enough. I'm going now before she arrives.
Ms. Rack: ...Yes, Master/Mistress.