Sayaka Kotegawa

She is Chisa and Nanaka's mother and the manager of Dophin diving pad at Palau, where Chisa, Iori, Kouhei and Aina work part-time during summer break. Sayaka is a serious and straightforward person, who doesn't talk beyond what is necessary and acts cold towards Chisa. ~!She is deaf in her left ear, because of constantly ear pressure during diving, and never told Chisa because she knows how much she loves diving.!~