Thompson, who has 66 international caps, qualified through residency to play for Japan in 2007 and featured in the World Cup that year, as well as in 2011 and '15. The 38-year-old Thompson was one of only 10 players with previous World Cup experience in the Japan squad that was announced on Thursday.
Japan, which recently won the Pacific Nations Cup, is in Pool A with Russia, Ireland, Samoa and Scotland.
Forwards: Keita Inagaki, Yusuke Kizu, Jiwon Koo, Isileli Nakajima, Asaeli Ai Valu, Takuya Kitade, Atsushi Sakate, Shota Horie, Luke Thompson, Wimpie van der Walt, Uwe Helu, James Moore, Hendrik Tui, Yoshitaka Tokunaga, Michael Leitch (captain), Pieter Labuschagne, Kazuki Himeno, Amanaki Lelei Mafi
Backs: Kaito Shigeno, Fumiaki Tanaka, Yutaka Nagare, Yu Tamura, Rikiya Matsuda, Kenki Fukuoka, Ataata Moeakiola, Lomano Lava Lemeki, William Tupou, Ryoto Nakamura, Timothy Lafaele, Kotaro Matsushima, Ryohei Yamanaka
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