During the next training session, Oikawa was probably late because of the rain that was pouring outside.

"And where is he..." Ushijima thought, looking at the gym door

The rain continued to fall hitting the windows of the room and the knocks of balls from the floor echoed throughout the area.

(POV author: 私はキヤノンを変えるのは好きではありませんが、他の考えはありませんでした。 失礼します (∩`ﾛ´)⊃)