Karuizawa Yuukai Annai

Kumiko and her younger sister Nagisa are spending their vacation in Karuizawa. One day Nagisa went out to the supermarket to do some shopping, but then failed to return to the villa they were staying at. Kumiko also receives a strange phone call later that night. With the police not being very helpful, Kumiko and her boyfriend (i.e. you) decide to take matters into their own hands. from http://pixelmenu.22web.net/features/enix/enix1.html

You are a college student on vacation with your girlfriend, when her sister Nagisa mysteriously disappears after going on a shopping trip. Investigate the kidnapping by sleuthing around the scenic town of Karuizawa.