https://www.dlsite.com/maniax/work/=/product_id/RJ01521843.html
https://www.dmm.co.jp/dc/doujin/-/detail/=/cid=d_663515/

「で でかっ… こんなの初めて見た… 作り物じゃないよね？」

偶然、一人暮らしをしているクラスでも低カーストのガリ勉陰キャの家に一晩泊めてもらう事になったプチ家出中のカースト上位ギャル。

ほんの気まぐれで一宿一飯の恩返しと陰キャ君の童貞を奪ってあげようとパンツを脱がしたらそこには規格外のイチモツが！。しかし怯まず舐めて咥えてハメてみたらさあ大変、たちまちギャルは陰キャのイチモツの虜に。

そこからハメられるたびに巨根にイカされまくりの連続、身も心も堕とされてついにはM属性を開花させられたギャルと陰キャは立場が逆転、めでたくメス犬へとなり下がったギャルの運命は如何に。

エッチから始まる二人の爛れた主従逆転イチャラブストーリーここに開幕！

Base +28, 流萤啾啾 +42

[Synopsis]

By chance, a high-class gal who has run away from home ends up staying overnight at the home of a low-class, studious and introverted guy who lives alone.
On a whim, she decides to repay the introvert's kindness by taking his virginity and takes off his pants to reveal an out-of-the-ordinary penis!
However, she doesn't flinch and when she licks and sucks it and puts it in her mouth, things get crazy - the gal is instantly captivated by the introvert's penis.
From then on, every time he puts it in, she is made to cum over and over again by his huge penis and as her body and mind are corrupted, her masochistic tendencies are finally awakened.
From then on, the roles of the gal and the introvert are reversed.
What will become of the gal who has been reduced to a bitch?

This is the beginning of a love story between two people, where the relationship of master and servant is reversed, starting with sex!

Base +31, Fofotron +28