Spending a Month with My Sister

Winter─ A time of year where people feel the need to run around every waking moment with a deluge of feelings in their hearts. The scenery in a new development near the urban center, Megumi City, only made that sentiment more prominent. Then, on Christmas Eve─

An utterly unremarkable young man runs into a mysterious girl while out on an errand. It is when he realizes this girl he has no memory of ever meeting is, for some reason, familiar to him that their story begins...

─One wishes to protect the fun times they share.
─Another has something to gain.
─The last is determined to accomplish their goal.

Each of their fates interleave into a tale.

The protagonist unexpectedly ends up letting a gyal high school girl, “Rio-chan,” stay at his home.
Improve yourself, earn money, and deepen your bond with Rio-chan.
The ending will change depending on how you spend your days and her affection level towards you.
With a limited cohabitation period of 30 days, whether you can reach a good ending is up to you!

Two sisters started living in my house for one simple reason: it was close to their school.
But each of them had their own hidden agenda.

"Big bro, please always keep at least 100 meters between you and Mikaru-nee!"
"Michiru, you’re the one who should stay away from Yuuhi-nii-san!"

Ah… my daily life is already a complete mess.
And just like that, my chaotic, nostalgic, and lively days with them began.

Your lazy sister is spending her money on new things.
Where is she even getting this money from?

You play as the Demon of Lust, disguised as a charming preacher who infiltrates a remote monastery with one simple mission: corrupt the holiest place in the region from the inside.
What starts as an easy task quickly turns into a game of psychology, manipulation, and control — because the nuns are far from innocent.

Each sister has her own personality, secrets, boundaries, and forbidden fantasies. By carefully managing daily schedules, making the right choices, and interacting with visitors, you guide them on a journey from strict devotion to forbidden self-discovery.