sister Love

It's a straightforward adult visual novel.
A sister and brother get caught in the rain, end up taking a bath together, and then... This story depicts the experience of a boy and his older sister.
Features plenty of large scrolling images, with some partial animation as well.
Alongside the story mode, there's also a CG gallery mode where you can review previously viewed CGs.
With no branching choices, anyone can make it to the end without getting stuck.
Total CG count: 48

[Translated from the DLsite]