The doubles partner of Aragaki Kōichi, who, having grown up playing under an extremely hot sun, have extremely high endurance, which makes up for not being able to use the "Shukuchihō" technique.
With the greatest lung capacity and endurance on the team (in the Manga, but in the Anime it's Aragaki), Shiranui holds out the longest during Higa's underwater stamina exercises. Nevertheless, he was completely worn out after his doubles match against Seigaku's Kaido and Inui.
Shiranui, like many players from Kyuushu and the Okinawa prefecture specifically, has a dark skin tone.
(Source: Prince of Tennis Wikia)