My Common Sense Alteration Life Spent with My Downer-Type Little Sister [v1.0] [Mogumogu Guards]

October 10, 2026F95

The protagonist happens to get his hands on a common sense alteration smartphone. Using the power of that app, he alters his little sister’s common sense, engaging in various erotic pranks and sexual acts in this daily life simulation game.
In this work, you can spend summer vacation days together with your little sister. Every day, you can engage in wholesome communication with her, such as conversing and skinship. On top of that, by adding new common sense alterations, various erotic choices will become available as well. Use the power of the common sense alteration app to spend a debauched summer vacation with your little sister!!

Thread Updated: 2026-10-09

Release Date: 2026-08-27

Original Name: ダウナー系妹と過ごす常識改変生活

Aliases: Downer-kei Imouto to Sugosu Joushiki Kaihen Seikatsu

Developer: Mogumogu Guards DLSite – Ci-en – Twitter

Translator: lynxwall____

Censored: Yes (Mosaics)

Version: 1.0

OS: Windows

Language: English (Opus 5.5)

Store: DLSite

Genre:

2DCG, Male Protagoist, Censored, Japanese Game, Big Tits, Creampie, Groping, Handjob, Incest, Oral Sex, Sex Toys, Vaginal Sex, Mind Control, Simulator,