モウイイカイ？

Even though she was my older sister, she was younger than me. In a remote mountain village, my sister disappeared, leaving behind a mysterious message. Left to fend for myself, I, her younger brother, come to uncover the village’s hidden secrets. What on earth happened to my sister…? Nostalgia, cruelty, and lyricism. A nostalgic and erotic legend begins. (Source: ebookjapan, translated)