The Girl in the Library: Until The Pure You Falls From Grace

The Girl in the Library: Until the Pure You Falls From Grace (Toshoshitsu No Kanojo ~Seiso Na Kimi Ga Ochiru Made~) is a short manga series written by Arare Ame and adapted into a four-episode OVA by Pink Pineapple faithfully using the first four chapters. While the manga was originally meant to end at chapter four, a fifth chapter was eventually made with a sixth chapter announced.

The story begins when a high school student, Yukiha Serizawa, while working as a library assistant with her crush, Aida, defends the janitor, Masami Kitou, after he's accused of breaking a vase. Masami, in turn rapes her while she's drugged while recording it and then blackmails her into being his sex slave. However, Masmai proves to be really good at sex which Yukiha begins to enjoy and eventually becomes his sex slave of her own free will.

Tropes used in The Girl in the Library: Until The Pure You Falls From Grace include:

Abusive Parents: Both Yukiha and Masami will become this. Masmai plans to rape his child if it's a girl or abort it if it's a boy, and Yukiha's become too much of a slut to care.
All for Nothing: The entirety of episode/chapter 2 is this, with Masami refusing to delete the sex video he made even after Yukiha humiliated herself.
Babies Ever After: Yukiha ends up pregnant with Masami's child when she become his sex slave willingly. Both are hoping for a girl so Masami can turn his own daughter into his sex slave as well.
The Bad Guy Wins: Masami not only gets away with raping Yukiha over and over, but she becomes his sex slave of her own free will.
Bigger Is Better in Bed: Sadly Masami is this trope which played a role in Yukiha becoming his sex slave willingly.
Blackmail: Masami threatens to release a sex tape he made when he raped Yukiha if she doesn't agree to be his sex slave.
Break the Cutie: Yukiha, a kind-hearted girl is repeatedly raped by the janitor and becomes so corrupted she becomes almost as bad a person as he is.
- Also Aida, a kind-hearted boy suffers an immense mental breakdown after the girl he loves dumps him for her own rapist.
Buxom Is Better: Masami believes Yukiha's boobs are F or G cup when he first sees them. Naturally he enjoys fondling them before raping her and having sex with her when she becomes his sex slave willingly.
Child by Rape: Averted, Yukiha becomes pregnant after she becomes Masami's sex slave willingly.
Defiled Forever: Masami took Yukiha's virginity when he raped her. Because of that she felt unworthy of Aida's love.
Derailing Love Interests: Played darkly here, Aida is a very friendly person but his poor sexual performance made Yukiha dump him for Masami.
Despair Event Horizon: Aida after Yukiha not only has sex with Masami while he watches on his phone but mocks his poor sexual performance. Even after six months, he's still not only traumatized, but became a shut-in with garbage piling up in his room.
Did Not Get the Girl: Aida not only doesn't get to be with Yukiha, but she openly mocks his poor performance on his phone while he's forced to watch her have sex with her own rapist willingly.
Dirty Old Man: Masami is possibly in his fifties but he forced Yukiha, a high school girl, to be his sex slave and eventually got her pregnant and even hopes to turn his future daughter into a sex slave as well. He even calls himself a dirty old man when he first rapes Yukiha.
Disproportionate Retribution: For his failure to make Yukiha experience an orgasm, Aida is forced to watch Yukiha have sex with Masami of her own free will while being mocked for his poor stamina and small penis. Aida's heart is not only broken but he suffers a complete mental breakdown he's still suffering from six months later.
Downer Ending: Episode 4 ends with Aida completely heartbroken, Yukiha presumably disowned by her parents, her reputation in school shattered and pregnant with Masami's child, whom he plans to rape if it's a girl and abort if it's a boy.
Even Evil Has Standards: When Yukiha went to Masami's house of her own free will, Masami himself warned her once she enters his house there'd be no going back.
- Yukiha was perfectly okay with breaking Aida's heart and mocking his performance, but for some reason she begged him not to look at her orgasm face.
Exact Words: In Chapter/Episode 2, Yukiha begs Masami to stop making her his sex slave. Masami agrees to give some thought about deleting the sex video he made if she humiliated herself at school wearing bondage straps and a vibrator jammed into her all day. When she's done, he begins fondling her again. When she tells him that he wasn't keeping his promise, he tells her he said he'd only give it some thought. Yukiha then realizes Masami had no intention of deleting that video.
The Farmer and the Viper: Yukiha's reward for saving Masami from being fired over a vase is to be raped and used as a sex slave through blackmail.
Face Heel Turn: Yukiha was corrupted by Masami's sexual prowess and became just as evil as he was by Chapter 5.
Fan Disservice: Masmai is a well-endowed sex god. But he's also an ugly bastard with hairy legs and is possibly in his 50s and is also a vile rapist.
- Yukiha going Naked Apron while pregnant. Doesn't stop Masami from having sex with her.
Faux Affably Evil: By chapter 5, Yukiha maintains a sweet and almost innocent personality, but assists Masami in raping her teacher, Takamine, showing she has become just as evil as he is.
Forced to Watch: Masami and Yukiha have sex while making Aida watch on his phone. While technically he could turn his phone off, seeing the love of his life mock and belittle him while having sex with her own rapist willingly leaves him too broken hearted and shocked to put the phone down. By the time he finally does stop watching, he's already suffered a mental breakdown.
Future Loser: Yukiha had a promising life ahead her her, a loving boyfriend, respected at school, a nice job, a stable home life, but she threw all that away to be a janitor's sex slave. Now she burned her bridges with her school, Aida and even her own parents have disowned her. She's still a teen but she's on the path to becoming this.
Gainaxing: Yukiha when she has sex with Masami.
Go Mad From The Revelation: Aida's heart is not only broken when Yukiha chooses her own rapist, but being forced to watch her have sex with Masami on his phone makes Aida suffer a complete mental breakdown he's still suffering from six months later.
- Yukiha has only ever had sex with Masami and even lost her virginity to him when he raped her, so when Aida fails to pleasure her, she tries in vain to reach orgasm by masturbation and realizes Masami is now the only one who can pleasure her.
Good People Have Good Sex: Unfortunately averted and inverted. Though Aida loves Yukiha, his poor performance in bed makes Yukiha dump him for her own rapist, becoming Evil People have Good Sex.
Happiness in Slavery: Yukiha becomes too dependent on Masami to sexually pleasure her that she becomes his sex slave willingly.
Hate Sink: Masami is a pervert that drugged and raped Yukiha shortly after she saved him from being fired over a vase and then recorded the rape and made her a sex slave by threatening to leak the video online. He then even humiliated Yukiha by making her put bondage straps over her clothes and jam a vibrator in her which he would activate when she was called on by her teachers. By the time Yukiha becomes his sex slave of her own free will and gets her pregnant, he makes it clear he wants his own unborn child to be another sex slave if it's a girl or abort if it's a boy.
- Yukiha herself becomes a hate sink when she chooses to be Masami's sex slave willingly and then broke Aida's heart by making him watch her and Masami have sex and cause him to suffer a mental breakdown. Once she's impregnated by Masami she also hopes to give birth to a daughter just to please Masami's desire. By the the fifth chapter, she assists Masami in raping her teacher and became just as evil as he is and destroying any sympathy she might have gotten as a rape victim.
Humiliation Conga: In episode/chapter 2, after raping Yukiha, Masami tells Yukiha he'd consider deleting the sex video on his phone if she'd place bondage straps under her school clothes with a vibrator jammed in her for the day. Whenever the teachers would call for her, Masami, watching through hidden cameras would activate the vibrator. When Aida confessed his love for Yukiha, Masami activated the vibrator before she could confess her love for him as well. In the end, he refused to delete the video.
Irony: For the first 3 chapters, Yukiha is frequently raped by Masami, but when Aida fails to make her experience an orgasm, she has to beg Masami for sex in the fourth chapter.
I Have No Daughter: It's strongly implied that Yuika's parents disowned her when she ran off with Masami and sex tapes about her were leaked. Not like she cares though since.
I Showed Her What A Real Man Is: Masami mocks Aida when Yukiha becomes his sex slave willingly.
I Was Quite a Looker: Backstories in the manga suggest Masami was quite handsome when he was much younger.
I Will Protect Her: Aida vows to protect Yukiha from Masami. It goes very wrong.
It Amused Me: The real goal Masami had in mind when Yukiha humiliated herself in Chapter/Episode 2.
"It's Not Rape If You Enjoyed It": Yukiha starts to enjoy sex with her rapist and dumps Aida for failing to pleasure her.
Karma Houdini: Masami gets away with his actions and gains Yukiha as a sex slave.
Making Love in All the Wrong Places: More like being raped in all the wrong places. Masami has raped Yukiha in the school library and a public restroom and didn't stop even when another person entered.
May-December Romance: Yukiha is a high school girl while Masami is a man in his 50s. However it is no romance.
Morton's Fork: In chapter/episode 4, Yukiha is torn between Aida and Masami. Masami offers her a choice: he'd actually back off and stop raping Yukiha if she decides to go with Aida, but she'd live a boring life with a boy with almost no sex drive but at least be with some someone who loves her. However if she'd pick Masami, she live her life as a sex slave with a man who has no love for her but is a well-endowed sex god.
Naked Apron: Yukiha wears it after being becoming Masami's sex slave willingly. Also she's pregnant while wearing it.
Netorare Genre: It begins near the end of episode/chapter 3 and goes into full force in episode/chapter 4 when Yukiha has sex with Masami of her own free will while openly mocking Aida as he watches.
Nice Guy: Aida, often helping Yukiha at the library and vowed to protect Yukiha from Masami.
No Pregger Sex: Very averted. Masami not only has sex with a six-month pregnant Yukiha, but even records it saying he'd be paid a lot of money for a sex video with a pregnant high schooler.
Official Couple: Yukiha and Masami, unfortunately.
Oh Crap: Yukiha does this twice. In chapter/episode 2, when she realizes Masami never planned to delete the sex tape even after she humiliated herself and again in chapter/episode 3 when she learns Masami knows where she lives.
Parental Incest: Masami plans to have sex with his own possible future daughter who hasn't even been born yet. Yukiha is perfectly okay with this.
Porn with Plot: Well if you can call it a plot.
Reality Ensues: This is how Masami threatening to leak the sex video he made when he raped Yukiha worked. Even though that could also incriminate him and get him arrested, that video on the internet would have also been very humiliating for Yukiha. And worse, it's extremely difficult to get something off the internet and most of the time, impossible so that video would end up haunting her for life.
Reasonable Authority Figure: The teacher Takamine is the only one who shows concern when both Yukiha and Aida disappeared from school.
Sex Face Turn: Inverted, Yukiha becomes corrupted and evil after she becomes Masami's sex slave.
Sex God: Masami is an ugly bastard and a vile rapist, but it can't be denied he is great at sex. When Yukiha become his sex slave willingly, they have sex until morning, at which point Yukiha is completely worn out. She describes sex with him as heaven. Even the act of sucking her nipples while licking them made Yukiha have a wild orgasm. Even when she performed fellatio on him, she got an orgasm.
Sex Slave: Yukiha was originally this due to blackmail, but as she becomes more slutty and corrupted, she becomes this of her own free will.
Single Woman Seeks Good Man: Yukiha originally fell in love with Aida because of his kind heart. However, his poor performance made her dump him to be Masami's sex slave instead.
Slipping a Mickey: How Masami raped Yukiha to begin with.
Slut Shaming: The sex tape made by Masami gets leaked out causing Yukiha to be expelled from school and disowned by her parents. Considering she's okay with her child being raped or aborted and aided in her teacher being raped, she deserves it.
Speed Sex: Aida, and it drove Yukiha into the arms of her own rapist.
Stay in the Kitchen: Six months after running off to be Masami's willing sex slave, she's completely disappeared from everyone she knew and is last seen cooking dinner for her and Masami, hinting she's never left his house, even when he's gone.
Teeny Weenie: Yukiha mocks Aida by saying he has the dick of a child. However this may be because Masami is much bigger. Nevertheless, this breaks Aida's heart.
Took a Level in Jerkass: Yukiha after she becomes Masami's sex slave willingly. She's implied to be perfectly okay with her possible future daughter being raped, or her possible son being aborted. She also mocked Aida's poor performance while he listens. In Chapter 5, she even helps Masami with raping Takamine, becoming just as evil as he is.
Ungrateful Bastard: Masami's reaction to Yukiha saving him from being fired is to rape her.
Victim Falls For Rapist: It's not so much Yuikiha falls in love with Masami, she just becomes a slut that just wants him for his sexual prowess. She did however offer her heart to him in return for sex.
Villain Has A Point: In Chapter/Episode 4, Masami offers to have sex with Yukiha if she tells Aida she offered her body and heart to him. When Yukiha shows some reluctance to do that, Masmai points out she left Aida to have sex with him.
Women Prefer Strong Men: While not muscular, Masami is definitely stronger than Aida and has an infinitely stronger sex drive. This is what makes Yukiha choose him over Aida.