A strong-willed, big-boobed karate girl gets turned into a super slut by her serious boyfriend's big-dicked brother!

* This work is the English translated version of "My Brother Fucked My Girlfriend Silly (RJ339437)"

A 25 page manga
Samples use mosaic censoring, but the full manga uses black bars.

[Story]
Tatsuro Higuchi is the son of a prestigious karate teacher who runs a dojo with a storied history. His girlfriend is Sumireko, a pretty girl and fellow karate student whom his parents have officially recognized as his future wife.

But one summer vacation, Tatsuro's older brother Ryoma comes to the dojo. Their father intends to whip him into shape and put and end to his philandering, school-skipping ways. Frustrated with his lazy brother, Tatsuro leaves for a week-long training camp, with Sumireko more than eager to oversee Ryoma's training...

Big mistake.

Ryoma slips something into Sumireko's drink one day, and when she wakes up she finds Ryoma looming over her. He says he has a video of him raping her, and if she doesn't agree to be his fuckbuddy for the whole week, he'll show it to Tatsuro!

If it's for her love, Sumireko will endure anything... but no kissing or raw sex are allowed! And that suits Ryoma just fine... after all, her simple, baseline knowledge of pleasure is no match for Ryoma's incredible dick!

"H-His... huge dick.. it's changing the shape of my vagina...!"

Manga: Sekai Ichi（Twitter: @Seka_ichi）
Script: Makafushigi-man（Twitter: @Rq7p4SxURBd9fVE）Sumireko Murasakizuka

The only daughter of a karate dojo. She is very serious about karate and never skips training. She is also an upstanding and straightforward person. She and Tatsuro were childhood friends and are now lovers. They often trained together as children. She is strong enough to overpower most men with her karate skills. However, this leads her to believe that she has no feminine charm.

She likes to make clothes and plushies in her free time. She's into strong, manly menTatsuro Higuchi

Sumireko's childhood friend. They often trained together at the dojo. He'd always liked her, but believed that he wouldn't be worthy of her if he wasn't strong. He then devoted himself to his training, becoming strong enough to win several tournaments. He is now finally dating Sumireko. Her family recognizes their relationship and accepts him as her future husband.

He has a lot of stamina, but no sexual ability. He also has an inferiority complex about his lack of sexual prowess.Ryoma Higuchi

Tatsuro's older brother. He is in college.
He'd always spent a lot of time playing around, but took things to the next level after entering college. Their father found out about his escapades and dragged him back home for summer vacation, forcing him to go to the dojo. He is a ladies' man and will have a go at most women, but never takes relationships seriously.
He has big dick bulging with veins, a fat shaft, and a huge glans.