let's_la_go!_bokura_no_jiyuu_kenkyuu
Summarized From VNDB:
It's summer vacation! It's time for free study but Koudai and three girls in his class aren't sure what theme to make for their summer study. Koudai has a map he found at his grandfather's home listing the location of treasures. If you collect all the treasures, you get to make a wish! But there's a catch. You need to search for the treasures naked!
Aliases: none