---
title: "Seikan Shimai"
description: "Due to messing with his grandfather's machine, the protagonist and his 2 cousins have switched body. They try to switch back right away but the machine breaks. "
image: "https://t.vndb.org/cv/22/107722.jpg"
---

# Seikan Shimai

![Seikan Shimai](https://t.vndb.org/cv/22/107722.jpg)

**Alternative Title:** 性換姉妹

**Aliases:** 性換スイッチ

**Developer:** Noir Soft

**Release date:** Apr 28, 2017

**Platform:** Windows, macOS, DVD, Switch

**Language:** Japanese, German, English, Spanish, French, Italian, Korean, Dutch, Portuguese (Portugal), Russian, Chinese (simplified), Chinese (traditional), Bulgarian, Finnish, Norwegian, Swedish, Vietnamese

**Rating:** 6.5/10 (31 votes)

## Description
Due to messing with his grandfather's machine, the protagonist and his 2 cousins have switched body. They try to switch back right away but the machine breaks. And thus, they are stuck inside each other's bodies for a while.

[Translated from [Official Site](http://www.noirsoft.co.jp/seikanshimai/index.html)]

## Characters
### Tokiwa Yuu (常盤 由宇)
[url=/c60992]Marina[/url] and [url=/c60993]Shizuku's[/url] cousin. He swaps places with them using their grandfather's machine. The three of them swap bodies often which puts them in various unique situations.

- **Gender:** Male
- **Hair:** Black, Brown, Odango, Waist Length+, Shoulder-length, Straight, Spiky Bangs, Sidehair
- **Clothes:** Sweater, Trousers, Shirt, Miniskirt, Ribbon Tie, Sailor School Uniform
- **Eyes:** Grey
- **Role:** Wife, Mother, Cousin, High School Student
- **Subject of:** Pregnancy
- **Engages in:** Body Swap

### Tokiwa Marina (常磐 麻莉奈)
A seemingly cool older sister who dotes on the protagonist.

[url=/c62808]Yuu[/url]'s cousin. She is a beautiful and intelligent female college student. Her style is so outstanding that every man who passes by her looks back at her. She is actually a pervert who dotes on her cousin Yuu, but she cannot be honest and treats him with a cold attitude.

- **Gender:** Female
- **Measurements:** Bust-Waist-Hips: 87-57-84cm, E cup
- **Hair:** Brown
- **Eyes:** Brown
- **Role:** Cousin, University Student
- **Personality:** Smart
- **Engages in:** Body Swap
- **Voiced by:** Minamijuuji Issei

### Tokiwa Shizuku (常磐 雫)
Full of energy, a younger sister who loves her older brother.

[url=/c62808]Yuu[/url]'s cousin. She is always smiling and friendly and is liked by many people. Although she loses to her older sister [url=/c60992]Marina[/url] in style and figure, she is said to be a big-breasted loli character due to her short height. Unlike her sister, she always shows off that she loves her brother.

- **Gender:** Female
- **Measurements:** Bust-Waist-Hips: 83-56-81cm, D cup
- **Hair:** Brown
- **Role:** Student, Cousin
- **Eyes:** Violet
- **Subject of:** Pregnancy
- **Engages in:** Body Swap
- **Voiced by:** Asai Komomo

### Kurusu Kokoro (来栖 小衣)
A childhood friend who is devoted to the protagonist.

A bright and kind childhood friend who lives next door. She likes [url=/c62808]Yuu[/url], but can't really tell him. Furthermore, Yuu has become a woman, making it even more difficult for her to talk about it. A pitiable girl whose efforts are often in vain. Her suffering continues...

- **Gender:** Female
- **Measurements:** Bust-Waist-Hips: 82-56-79cm, D cup
- **Hair:** Violet
- **Eyes:** Violet
- **Role:** Childhood Friend, High School Student
- **Voiced by:** Tsukinaga Rito

## Shops
- [Official Website](http://www.noirsoft.co.jp/seikanshimai/index.html)
- [Steam](https://store.steampowered.com/app/2442610/)
- [DLsite](https://www.dlsite.com/pro/work/=/product_id/VJ010990.html)
- [Getchu](http://www.getchu.com/soft.phtml?id=944546)

## Releases
### Japanese
- **2017-04-28**: Seikan Shimai - Package Edition - [Official website](http://www.noirsoft.co.jp/seikanshimai/index.html), [ErogameScape](https://erogamescape.dyndns.org/~ap2/ero/toukei_kaiseki/game.php?game=24846), [Getchu](http://www.getchu.com/soft.phtml?id=944546)
- **2017-04-28**: Seikan Shimai - Download Edition - [Official website](http://www.noirsoft.co.jp/seikanshimai/index.html), [ErogameScape](https://erogamescape.dyndns.org/~ap2/ero/toukei_kaiseki/game.php?game=24846), [DLsite](https://www.dlsite.com/pro/work/=/product_id/VJ010990.html), [Gyutto](https://gyutto.com/i/item187475), [Digiket](https://www.digiket.com/work/show/_data/ID=ITM0153817/), [DL.Getchu](http://dl.getchu.com/i/item1005803), [DMM](https://dlsoft.dmm.co.jp/detail/russ_0225/)
- **2018-02-22**: Seikan Shimai - DVDPG - [Official website](http://www.n43project.com/n43/npg279/index.html), [DMM](https://www.dmm.co.jp/mono/anime/-/detail/=/cid=h_107npg279/)
- **2023-06-22**: Bijin Shimai to Irekawari Seikatsu -Becoming Your Beautiful Cousin- - [ErogameScape](https://erogamescape.dyndns.org/~ap2/ero/toukei_kaiseki/game.php?game=35117), [Nintendo (JP)](https://store-jp.nintendo.com/item/software/D70010000068544)
- **2023-07-06**: Bijin Shimai to Irekawari Seikatsu -Becoming Your Beautiful Cousin- - [ErogameScape](https://erogamescape.dyndns.org/~ap2/ero/toukei_kaiseki/game.php?game=35116), [Steam](https://store.steampowered.com/app/2442610/), [SteamDB](https://steamdb.info/app/2442610/info/)

### German
- **2023-06-22**: Bijin Shimai to Irekawari Seikatsu -Becoming Your Beautiful Cousin- - [ErogameScape](https://erogamescape.dyndns.org/~ap2/ero/toukei_kaiseki/game.php?game=35117), [Nintendo (JP)](https://store-jp.nintendo.com/item/software/D70010000068544)
- **2023-07-06**: Bijin Shimai to Irekawari Seikatsu -Becoming Your Beautiful Cousin- - [ErogameScape](https://erogamescape.dyndns.org/~ap2/ero/toukei_kaiseki/game.php?game=35116), [Steam](https://store.steampowered.com/app/2442610/), [SteamDB](https://steamdb.info/app/2442610/info/)

### English
- **2023-06-22**: Bijin Shimai to Irekawari Seikatsu -Becoming Your Beautiful Cousin- - [ErogameScape](https://erogamescape.dyndns.org/~ap2/ero/toukei_kaiseki/game.php?game=35117), [Nintendo (JP)](https://store-jp.nintendo.com/item/software/D70010000068544)
- **2023-07-06**: Bijin Shimai to Irekawari Seikatsu -Becoming Your Beautiful Cousin- - [ErogameScape](https://erogamescape.dyndns.org/~ap2/ero/toukei_kaiseki/game.php?game=35116), [Steam](https://store.steampowered.com/app/2442610/), [SteamDB](https://steamdb.info/app/2442610/info/)

### Spanish
- **2023-06-22**: Bijin Shimai to Irekawari Seikatsu -Becoming Your Beautiful Cousin- - [ErogameScape](https://erogamescape.dyndns.org/~ap2/ero/toukei_kaiseki/game.php?game=35117), [Nintendo (JP)](https://store-jp.nintendo.com/item/software/D70010000068544)
- **2023-07-06**: Bijin Shimai to Irekawari Seikatsu -Becoming Your Beautiful Cousin- - [ErogameScape](https://erogamescape.dyndns.org/~ap2/ero/toukei_kaiseki/game.php?game=35116), [Steam](https://store.steampowered.com/app/2442610/), [SteamDB](https://steamdb.info/app/2442610/info/)

### French
- **2023-06-22**: Bijin Shimai to Irekawari Seikatsu -Becoming Your Beautiful Cousin- - [ErogameScape](https://erogamescape.dyndns.org/~ap2/ero/toukei_kaiseki/game.php?game=35117), [Nintendo (JP)](https://store-jp.nintendo.com/item/software/D70010000068544)
- **2023-07-06**: Bijin Shimai to Irekawari Seikatsu -Becoming Your Beautiful Cousin- - [ErogameScape](https://erogamescape.dyndns.org/~ap2/ero/toukei_kaiseki/game.php?game=35116), [Steam](https://store.steampowered.com/app/2442610/), [SteamDB](https://steamdb.info/app/2442610/info/)

### Italian
- **2023-06-22**: Bijin Shimai to Irekawari Seikatsu -Becoming Your Beautiful Cousin- - [ErogameScape](https://erogamescape.dyndns.org/~ap2/ero/toukei_kaiseki/game.php?game=35117), [Nintendo (JP)](https://store-jp.nintendo.com/item/software/D70010000068544)
- **2023-07-06**: Bijin Shimai to Irekawari Seikatsu -Becoming Your Beautiful Cousin- - [ErogameScape](https://erogamescape.dyndns.org/~ap2/ero/toukei_kaiseki/game.php?game=35116), [Steam](https://store.steampowered.com/app/2442610/), [SteamDB](https://steamdb.info/app/2442610/info/)

### Korean
- **2023-06-22**: Bijin Shimai to Irekawari Seikatsu -Becoming Your Beautiful Cousin- - [ErogameScape](https://erogamescape.dyndns.org/~ap2/ero/toukei_kaiseki/game.php?game=35117), [Nintendo (JP)](https://store-jp.nintendo.com/item/software/D70010000068544)
- **2023-07-06**: Bijin Shimai to Irekawari Seikatsu -Becoming Your Beautiful Cousin- - [ErogameScape](https://erogamescape.dyndns.org/~ap2/ero/toukei_kaiseki/game.php?game=35116), [Steam](https://store.steampowered.com/app/2442610/), [SteamDB](https://steamdb.info/app/2442610/info/)

### Dutch
- **2023-06-22**: Bijin Shimai to Irekawari Seikatsu -Becoming Your Beautiful Cousin- - [ErogameScape](https://erogamescape.dyndns.org/~ap2/ero/toukei_kaiseki/game.php?game=35117), [Nintendo (JP)](https://store-jp.nintendo.com/item/software/D70010000068544)
- **2023-07-06**: Bijin Shimai to Irekawari Seikatsu -Becoming Your Beautiful Cousin- - [ErogameScape](https://erogamescape.dyndns.org/~ap2/ero/toukei_kaiseki/game.php?game=35116), [Steam](https://store.steampowered.com/app/2442610/), [SteamDB](https://steamdb.info/app/2442610/info/)

### Portuguese (Portugal)
- **2023-06-22**: Bijin Shimai to Irekawari Seikatsu -Becoming Your Beautiful Cousin- - [ErogameScape](https://erogamescape.dyndns.org/~ap2/ero/toukei_kaiseki/game.php?game=35117), [Nintendo (JP)](https://store-jp.nintendo.com/item/software/D70010000068544)
- **2023-07-06**: Bijin Shimai to Irekawari Seikatsu -Becoming Your Beautiful Cousin- - [ErogameScape](https://erogamescape.dyndns.org/~ap2/ero/toukei_kaiseki/game.php?game=35116), [Steam](https://store.steampowered.com/app/2442610/), [SteamDB](https://steamdb.info/app/2442610/info/)

### Russian
- **2023-06-22**: Bijin Shimai to Irekawari Seikatsu -Becoming Your Beautiful Cousin- - [ErogameScape](https://erogamescape.dyndns.org/~ap2/ero/toukei_kaiseki/game.php?game=35117), [Nintendo (JP)](https://store-jp.nintendo.com/item/software/D70010000068544)

### Chinese (simplified)
- **2023-06-22**: Bijin Shimai to Irekawari Seikatsu -Becoming Your Beautiful Cousin- - [ErogameScape](https://erogamescape.dyndns.org/~ap2/ero/toukei_kaiseki/game.php?game=35117), [Nintendo (JP)](https://store-jp.nintendo.com/item/software/D70010000068544)
- **2023-07-06**: Bijin Shimai to Irekawari Seikatsu -Becoming Your Beautiful Cousin- - [ErogameScape](https://erogamescape.dyndns.org/~ap2/ero/toukei_kaiseki/game.php?game=35116), [Steam](https://store.steampowered.com/app/2442610/), [SteamDB](https://steamdb.info/app/2442610/info/)

### Chinese (traditional)
- **2023-06-22**: Bijin Shimai to Irekawari Seikatsu -Becoming Your Beautiful Cousin- - [ErogameScape](https://erogamescape.dyndns.org/~ap2/ero/toukei_kaiseki/game.php?game=35117), [Nintendo (JP)](https://store-jp.nintendo.com/item/software/D70010000068544)
- **2023-07-06**: Bijin Shimai to Irekawari Seikatsu -Becoming Your Beautiful Cousin- - [ErogameScape](https://erogamescape.dyndns.org/~ap2/ero/toukei_kaiseki/game.php?game=35116), [Steam](https://store.steampowered.com/app/2442610/), [SteamDB](https://steamdb.info/app/2442610/info/)

### Bulgarian
- **2023-07-06**: Bijin Shimai to Irekawari Seikatsu -Becoming Your Beautiful Cousin- - [ErogameScape](https://erogamescape.dyndns.org/~ap2/ero/toukei_kaiseki/game.php?game=35116), [Steam](https://store.steampowered.com/app/2442610/), [SteamDB](https://steamdb.info/app/2442610/info/)

### Finnish
- **2023-07-06**: Bijin Shimai to Irekawari Seikatsu -Becoming Your Beautiful Cousin- - [ErogameScape](https://erogamescape.dyndns.org/~ap2/ero/toukei_kaiseki/game.php?game=35116), [Steam](https://store.steampowered.com/app/2442610/), [SteamDB](https://steamdb.info/app/2442610/info/)

### Norwegian
- **2023-07-06**: Bijin Shimai to Irekawari Seikatsu -Becoming Your Beautiful Cousin- - [ErogameScape](https://erogamescape.dyndns.org/~ap2/ero/toukei_kaiseki/game.php?game=35116), [Steam](https://store.steampowered.com/app/2442610/), [SteamDB](https://steamdb.info/app/2442610/info/)

### Swedish
- **2023-07-06**: Bijin Shimai to Irekawari Seikatsu -Becoming Your Beautiful Cousin- - [ErogameScape](https://erogamescape.dyndns.org/~ap2/ero/toukei_kaiseki/game.php?game=35116), [Steam](https://store.steampowered.com/app/2442610/), [SteamDB](https://steamdb.info/app/2442610/info/)

### Vietnamese
- **2023-07-06**: Bijin Shimai to Irekawari Seikatsu -Becoming Your Beautiful Cousin- - [ErogameScape](https://erogamescape.dyndns.org/~ap2/ero/toukei_kaiseki/game.php?game=35116), [Steam](https://store.steampowered.com/app/2442610/), [SteamDB](https://steamdb.info/app/2442610/info/)

## Tags
ADV, Lesbian Sex, Male Protagonist, Protagonist's Childhood Friend as a Heroine, Nukige, Group Sex of One Male and Several Females, Group Sex of One Female and Several Males, Cousin Incest, Protagonist's Cousin as a Heroine, Body Swapping, Defloration, Cunnilingus, Genderbent Sex, Facesitting, Double Handjob, Rimming Handjob, Heroine with Big Breasts, Body Swapped Sex

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---
*View the full details at [pinovel.net/v20656](https://pinovel.net/v20656).*

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```