Based on the provided source material, there is no information identifying Yokoshima as a city in Japan. Instead, Yokoshima is identified as a Japanese surname.
Notable individuals with the surname Yokoshima include athletes and professionals such as Aya Yokoshima and Kaoru Yokoshima, who are both handball players; Hisashi Yokoshima, a racing driver; and Yoshikazu Yokoshima, a golfer.