---
title: "G-Cup Sisters! ~Imouto Darake no Sakunyuu Gakuensai~"
description: "New teacher Ukima Sousuke is assigned to Kamomiya Academy and is passionate about his dream job as a teacher. But at home, Sousuke is also the older brother of "
image: "https://t.vndb.org/cv/15/142115.jpg"
---

# G-Cup Sisters! ~Imouto Darake no Sakunyuu Gakuensai~

![G-Cup Sisters! ~Imouto Darake no Sakunyuu Gakuensai~](https://t.vndb.org/cv/15/142115.jpg)

**Alternative Title:** Gカップシスターズ！ ～妹だらけの搾乳学園祭～

**Developer:** Marine

**Release date:** Sep 18, 2015

**Platform:** Windows

**Language:** Japanese, English

**Rating:** 7.3/10 (81 votes)

## Description
New teacher Ukima Sousuke is assigned to Kamomiya Academy and is passionate about his dream job as a teacher.
But at home, Sousuke is also the older brother of three younger sisters.
Himari, the eldest, is a soft-spoken, airhead.
Yuzuki, the second, is reliable and clingy.
Mio, the third, is a devilish teaser.
The three younger sisters, who have been attached to their older brother since childhood, all enrolled at his school.

When the brother starts working as a teacher, Sousuke takes advantage of the situation and becomes a siscon, clinging to them from the time he wakes up to the time he goes to and from school, and even around the school at all times.
However, perhaps all of their growth has been focused on their breasts, as while they haven't grown in height, their breasts have grown into an incredibly large G-cup.

As a result, all of his siscon behavior, which has remained unchanged since childhood, is now fueling his desires as a man.
As he grapples with his complicated feelings toward his younger sisters as both a brother and a man, one day, the school festival approaches.

Sousuke stayed behind after school when his younger sister Himari came in with tears in her eyes.
"I... I've started producing milk! What, what, what should I do, Onii-chan..."

Sousuke tried to calm her down, but was at a loss as to what to do. Himari timidly spoke up.

"Um, you see... Onii-chan... Um, can you... Squeeze my breasts... Is that okay?"

Even if she's your sister, massaging a woman's breasts and squeezing breast milk out of her... There's no way a teacher would allow that!

Sousuke tried to restrain himself with common sense and reason, but Himari pressed her 
G-cup breasts together and looked up at him, pleading.
"Please, Onii-chan... I ask you to do this... You're the only one I can ask..."

Those words instantly broke Sousuke's reason, and he listened to his sister's request and agreed to squeeze her breast milk.

She has a cute appearance and is on the short side. And her breasts are a G cup.
How long will Sousuke be able to keep his sanity as he squeezes breast milk at the request of his sisters...?

## Characters
### Ukima Sousuke (浮間 奏介)
The protagonist and the oldest sibling of the Ukima family. He is the newly appointed assistant homeroom teacher of Himari's class. His appearance is very lacking, however, he is very kind person due to having always taken care of his little sisters.

- **Gender:** Male
- **Hair:** Black, Short, Eye Covering, Spiky Bangs, Pubic Hair
- **Body:** Pale, Young-adult, Muscular
- **Clothes:** Trousers, T-shirt
- **Role:** Husband, Father, Full Brother, Teacher, Coworker, Older Brother
- **Engages in:** Teasing, Polygamy, Wedding
- **Personality:** Kind, Sister Complex
- **Subject of:** Flirting, Seduction

### Funado Miki (舟渡 美姫)
"M-My boobs, they have pretty depressing... nipples. Please don't laugh when you see them, okay?"The homeroom teacher of Himari's class and Sousuke's senpai.

- **Gender:** Female
- **Measurements:** Height: 149cm, G cup
- **Hair:** Twin Tails, Shoulder-length, Intake, Spiky Bangs, Orange, Sidehair
- **Body:** Slim, Pale, Young-adult, Inverted Nipples
- **Eyes:** Green
- **Clothes:** Kemonomimi Headband, Gloves, Skirt, Miniskirt, Tank Top, Wedding Dress, Garter Belt Stockings, Cuffs, Turtleneck Sweater, Clothing with Ribbons, Veil, Ribbon Hair Tie, Fishnet Stockings, Bunny Dress, Choker, Off-The-Shoulder Shirt, Microskirt
- **Personality:** Low Self-esteem, Strict, Relaxed, Smart, Watashi
- **Engages in:** Drinking, Lactation, Childbirth, Wedding
- **Role:** Wife, Mother, Teacher, Coworker, Popular
- **Subject of:** Pregnancy
- **Voiced by:** Misonoo Mei

### Ukima Himari (浮間 ひまり)
"U-Umm, so... Onii-chan... You don't want to squeeze my boobs?"The oldest sister of the family, Himari is naturally airheaded but a very honest girl who is also an obvious brocon. She normally behaves like a spoiled girl when she's around her onii-chan, however, but she starts acting like an older sister whenever her younger sisters start fighting.

- **Gender:** Female
- **Measurements:** Height: 148cm, G cup
- **Hair:** Pink, Violet, Ahoge, Odango, Waist Length+, Wavy, Intake, Spiky Bangs, Sidehair
- **Body:** Teen, Slim, Pale
- **Clothes:** School Uniform, Dress, Mini-dress, T-shirt, Gloves, Sport Bloomers, Boots, Thigh-high Stockings, Hoodie, Wedding Dress, Garter Belt Stockings, Detached Sleeves, High Heels, Naked Apron, Sports Uniform, Blouse, Clothing with Ribbons, Flower, Veil, Ribbon Hair Tie, Fishnet Stockings, Cheerleading Uniform, Bib, Slit Dress
- **Engages in:** Cooking, Sports, Lactation, Childbirth, Wedding
- **Eyes:** Blue
- **Personality:** Airhead, Friendly, Honest, Brother Complex
- **Role:** Wife, Mother, Full Sister, Cheerleader, High School Student, Younger Sister, Older Sister
- **Subject of:** Pregnancy
- **Items:** Pen
- **Voiced by:** Himekawa Airi

### Ukima Mio (浮間 澪)
"Is Mio serious? If it'll make Onii happy, then I'll do even more awesome things to you♪"The youngest sister who loves the protagonist very much and is very mischievous.

- **Gender:** Female
- **Measurements:** Height: 146cm, G cup
- **Hair:** Pink, Violet, Twin Tails, Long, Intake, Sidehair
- **Body:** Teen, Slim, Pale, Fang
- **Clothes:** School Uniform, Apron, Mini-dress, T-shirt, Gloves, Thigh-high Stockings, Hoodie, Wedding Dress, Garter Belt Stockings, Naked Apron, Sports Uniform, Strapless Dress, Clothing with Ribbons, Flower, Veil, Spats, Maid's Headdress, Old Type School Swimsuit, String Ribbon Tie, Bib
- **Engages in:** Cooking, Teasing, Sports, Flirting, Kigurumi, Seduction, Lactation, Childbirth, Wedding
- **Eyes:** Violet
- **Personality:** Shy, Energetic, Brother Complex, Third Person, Manipulative
- **Role:** Wife, Mother, Full Sister, Kouhai, High School Student, Younger Sister
- **Subject of:** Pregnancy
- **Voiced by:** Hayase Yayoi

### Ukima Yuzuki (浮間 結月)
The middle sister who has a very serious and firm personality. She rarely talks to the protagonist at school and acts quite cold towards him, but in reality just wants to be spoiled by him. She often bickers with Mio and is jealous of her for the fact that she is always around the protagonist.

- **Gender:** Female
- **Measurements:** Height: 151cm, G cup
- **Hair:** Blue, Ahoge, Hime Cut, Waist Length+, Intake, Sidehair
- **Body:** Teen, Slim, Pale
- **Clothes:** School Uniform, Pajamas, Headband, Vest, Gloves, Jeans, Boots, Thigh-high Stockings, Wedding Dress, Garter Belt Stockings, Naked Apron, Blouse, Flower, Veil, Ribbon Hair Accessory, Bib
- **Engages in:** Cooking, Lactation, Childbirth, Wedding
- **Eyes:** Violet
- **Role:** Wife, Mother, Full Sister, High School Student, Honor Student, Middle Sister
- **Subject of:** Pregnancy, Teasing
- **Personality:** Serious, Brother Complex, Jealous, Watashi
- **Voiced by:** Kitano Ari

## Shops
- [Official Website](http://www.lune-soft.jp/game/8871)
- [DLsite](https://www.dlsite.com/pro/work/=/product_id/VJ009437.html)

## Releases
### Japanese
- **2015-09-18**: G-Cup Sisters! ~Imouto Darake no Sakunyuu Gakuensai~ Package Edition - [Official website](http://www.lune-soft.jp/game/8871), [ErogameScape](https://erogamescape.dyndns.org/~ap2/ero/toukei_kaiseki/game.php?game=22113)
- **2015-09-18**: G-Cup Sisters! ~Imouto Darake no Sakunyuu Gakuensai~ Download Edition - [Official website](http://www.lune-soft.jp/game/8871), [ErogameScape](https://erogamescape.dyndns.org/~ap2/ero/toukei_kaiseki/game.php?game=22113), [DLsite](https://www.dlsite.com/pro/work/=/product_id/VJ009437.html), [Digiket](https://www.digiket.com/work/show/_data/ID=ITM0123721/), [DMM](https://dlsoft.dmm.co.jp/detail/mgold_0097/)

### English
- **2022**: G-Cup Sisters! ~Imouto Darake no Sakunyuu Gakuensai~ - [Official website](https://sugoivisualnovel.up.railway.app/vns/17729)

## Tags
Heroine with Big Breasts, ADV, Incest, Blood-related Incest, Brother/Sister Incest, Male Protagonist, Teacher Heroine, Nameable Protagonist, Nukige, High Sexual Content, Group Sex of One Male and Several Females, Pregnant Sex, Teacher Protagonist, Unlockable Harem Ending, Defloration, Sex in Public Places, Boobjob, Only Virgin Heroines, Sounds of Copulation, Lactation During Sex, Inbreeding, Intercrural Sex, Ejaculation Forewarner, Brocon Heroine, Naked Sprites, Siscon Protagonist, Shimaidon Ending, Soapy Massage, Marriage Ending, Twin Boobjob, Voiced Default Name, Triple Boobjob, Heroine with Inverted Nipples, Adult Breast Sucking, High School Student Heroine, Protagonist's Younger Sister as a Heroine, Protagonist's Full Sister as a Heroine, Blood-related Brother/Sister Incest

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---
*View the full details at [pinovel.net/v17729](https://pinovel.net/v17729).*

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