Adult PC Game: Yamete! Onee-chan!! Shiroi Oshikko ga Dechau by Yuuseiran jap Archive

Yu younger brother, Miu older sister:
Miu took care of her younger brother too much with her love and care.
However, their parents were worried about her excessive love for her brother.
And they decide to send Miu away from his brother, to a boarding school.
As the years passed, there was no connection between brother and sister, but in the end Miu returned home after graduating from boarding school.
However, her attitude towards him completely changed.
The former loving and caring elder sister was now cold and reticent.
With her parents present, Miu was forced to erect a wall between herself and Yu, barricading her true feelings.
However, as soon as her parents left, Miu instantly changed her personality.
Unfortunately, Yu was careful. He wanted to make amends.

Yamete! Onee-chan!! Shiroi Oshikko ga Dechau by Yuuseiran jap Gameplay Preview