KATANEGAI

Seiya and his sister Nagi return to their empty home village after their parents' deaths, settle into a quiet two-person life, and then Nagi falls gravely ill. There's no dramatic buildup beyond that: it's a small, sad household suddenly running out of options.

Looking for a cure, Seiya visits the local shrine and meets Yami, a shrine maiden dressed in black who tells him the only way to save Nagi is for the two siblings to "unite." The story frames this as breaking one wish to grant another, and it doesn't pretend the choice is easy.

It plays as a visual novel: read, choose, watch the consequences land across multiple endings, with voiced dialogue carrying the quieter scenes. The art is 2D and stays fairly close to the two leads and their shrinking world rather than sprawling outward.