Jones has though added to the squad with Shota Horie, Fumiaki Tanaka and Michael Leitch all called in.
Hooker Horie and scrumhalf Tanaka have both started games in recent weeks for the Rebels and Highlanders, respectively, while flanker Leitch has spent the last few months in New Zealand as part of the Chiefs expanded squad.
"After the successful Asian 5 Nations, we have now picked a squad that we believe can win the Pacific Nations Cup and beat Wales and we're looking forward to having Horie, Leitch and Tanaka back in the squad after the Super Rugby," Jones said prior to going into camp with his players.
A number of players who picked up knocks during the A5N or were rested for the latter stages have also been included, including Toshiaki Hirose who led the side in the first two tests before damaging a hamstring.
"We realize that we need to keep working very hard on our strength and conditioning and the way we play the game, and hopefully guys like Hirose will rehab quickly and be back for selection as soon as possible," Jones said, adding that Masakazu Nagano would also train with the squad.
To help with the increased physicality of the games ahead, Fabio Ongaro (capped 80 times by Italy) and Marc Dal Maso (who won 33 caps for France) will work with the squad as spot coaches.
The Brave Blossoms open their summer campaign against Tonga in Yokohama on May 25, before travelling to Fiji for a match on June 1.
They then return to Japan to play Wales on June 8 (in Osaka) and 15 (Tokyo), before wrapping up their PNC campaign with games against Canada and the United States on June 19 in Nagoya and June 23 in Tokyo
Ryu Koliniasi HOLANI