Kazuhiro belongs to Norimichi and Yusuke's school friend circle. He actively joins the boys' central debate over whether fireworks appear flat or round when seen from the side, showing his interest in settling the question through firsthand observation. This shared curiosity drives the group to plan a trip to the local lighthouse for a better view during the fireworks festival.

During Norimichi's first altered reality experience following a time rewind, Kazuhiro witnesses the fireworks transforming into flat planar shockwaves instead of their usual round shape. Norimichi directly addresses Kazuhiro at this moment, acknowledging the bizarre visual effect while simultaneously trying to minimize its importance. Kazuhiro remains with the friend group in the timelines that follow, including when they all pursue Norimichi and Nazuna after seeing them board the train.