Spring, a Date, and Playing a Little Sister

Spring, a Date, and an Imaginary Little Sister (春とデートと妹ごっこ) is a Drama CD released on January 6, 2012. The story take place between the events of Pentagon++ and Nise Random. This Drama CD marks the debut of Uwa Chihiro and Enjouji Shino's voice actors.

Summary
On an otherwise normal day, the five original members of the Student Cultural Society come across a bizarre note. Written on the note are the names of the second year members and "Fulfill the wishes of Enjouji and Chihiro." The second years immediately suspect it to be another message from Heartseed or No.2. As a result, the original five members decide to ask Enjouji and Chihiro if they need anything, doing their best to grant any wishes they have.