Zankou Noise summary:

From MangaHelpers: This manga is a collection of yuri romance short stories. Most of the stories take place in school, though one features an idol group. A few stories involve sexual situations, but others are more focused on feelings and tension. The first story features a girl whose secret place to be alone is discovered by a popular girl from school. Other stories include an ambiguous relationship at an all-girl's school, a girl who meets a gorgeous exchange student, and a trip to buy lingerie that ends up in an unexpected situation.