Luke Thompson will become the sixth oldest player to have competed at a Rugby World Cup if selected for Japan's opening match against Russia at the Tokyo Stadium on 20 September.
The 38-year-old, capped 65 times by the Brave Blossoms, will be 38 years and 157 days old by the time the game's showpiece tournament kicks off.
Thompson, who made his Rugby World Cup debut back in 2007, is one of the more experienced members of Japan's Rugby World Cup squad which also includes a veteran of the last two tournaments in hooker Shota Horie.
Horie's fellow hooker, Suntory Sungoliath's Takuya Kitade, is the only uncapped member of a squad that will be led for the second successive Rugby World Cup by back-row stalwart Michael Leitch.
Hosts Japan famously won three games at RWC 2015 under Eddie Jones, including an astonishing 34-32 victory over two-time champions South Africa, and narrowly missed out on a place in the quarter-finals.
Buoyed by the home support, head coach Jamie Joseph is hoping his side can make history four years on.
"The team has set a goal of making the top eight for the first time in the history of Japanese rugby," Joseph said.
"The staff and players will give 150 per cent – whether that's enough only time will tell.
"Our game is based around speed, skill and unstructured rugby. But the key difference this year is we are fit enough now to play that game. We're training at a level of intensity that's 25 per cent higher than our matches – I think that's our key weapon."
Currently ranked ninth in the world after capturing their third World Rugby Pacific Nations title, the Japanese also take on Ireland, Scotland and Samoa in Pool A as they target a place in the knockout stage for the first time.
Japan RWC 2019 squad
Forwards: Keita Inagaki, Yusuke Kizu, Koo Ji-won, Isileli Nakajima, Asaeli Ai Valu, Takuya Kitade, Atsushi Sakata, Shota Horie, Luke Thompson, Wimpie van der Walt, Uwe Helu, James Moore, Hendrik Tui, Yoshitaka Tokunaga, Michael Leitch (captain), Pieter Labuschagne, Kazuki Himeno, Amanaki Mafi
Backs: Kaito Shigeno, Fumiaki Tanaka, Yutaka Nagare, Yu Tamura, Rikiya Matsuda, Kenki Fukuoka, Ataata Moeakiola, Lomano Lemeki, William Tupou, Ryoto Nakamura, Timothy Lafaele, Kotaro Matsushima, Ryohei Yamanaka