Kokoro Connect Light Novel Volume 03

Kokoro Connect (ココロコネクト) is a Japanese light novel series written by Sadanatsu Anda, with illustrations by Shiromizakana. Volume 3 was released on September 30, 2010. This volume was adapted in the anime episodes 11 to 13.

Summary
With their 2nd semester at Yamaboshi High over, the Student Cultural Society looks forward to their Winter Break, but Heartseed, or rather, a mysterious new presence similar to Heartseed, has other plans for the club members. A new phenomenon occurs that causes members to physically and mentally revert to younger ages, and with their restored youth comes restored memories; memories that the StuCS members would rather keep locked away. In the midst of the confusion, Taichi strangely remains the only member unaffected by the phenomenon. What does this new presence want from the Cultural Club?

Trivia

 * "Kako" (過去) translates to "Past."
 * This volume has the most major changes in the anime version from the novel version.