C3 (C cubed) XV

is the fifteenth volume of the C3 light novel series, written by Hazuki Minase and Illustrated by Sasorigatame. It was released under the Dengeki Bunko Imprint in October 2012.

Synopsis
Haruaki's father, Kakuka, returns for a short while to the joy of regaining this. ...... For some reason she looks like a young woman. Haruaki reveals his distrust in the summer when he doesn't talk much. On the other hand, Haruaki's birthday is approaching, and the girls are on the rise. On the day of the event, the group decided to go to the sea at the suggestion of a summer break. Fear and her friends enjoyed swimming and bargaining for Haruaki, but what appeared in front of them was the division leader of the Ryushima / Ryuto Division!

(source: Bookwalker JP - Translated)

Characters

 * Haruaki Yachi
 * Fear Kubrick
 * Konoha Muramasa
 * Kirika Ueno
 * Sovereignty
 * Shiraho Sakuramairi
 * Kuroe Ningyouhara