Appearing in Episode 4, Ayuko Hayami (often mistranslated as Ayuko Hayamizu) is a former Olympic swimming medalist that now works as a swimming coach. Upon first seeing her, Kintaro is immediately enamored and describes her as "The Beast": an untamed wilderness that was able to awaken the "beast" in his heart. He applies to be a swimming coach at her school, but after failing to meet even adequate swimming standards, Kintaro challenges her to a swimming competition in a month's time of training. If he wins, Ayuko must accept him as a swimming coach. But if she wins, Kintaro is forced to do her bidding for an entire year.