The former Arsenal defender has been working with Pierre Sage's squad during their pre-season camp in Como and could feature in one of Palace's upcoming friendlies, having become available after his short-term deal at Ajax expired at the end of the season, says The Sun.
Crystal Palace are bracing for the departure of centre-back Maxence Lacroix, who is closing in on a £52m move to Chelsea, leaving Sage short at the back as he prepares for his first full campaign since replacing Oliver Glasner. Oscar Mingueza is so far the only confirmed arrival at Selhurst Park this summer.
It caps a turbulent 12 months for the 27-year-old, who agreed to terminate his Arsenal contract a year early last July after undergoing knee surgery in February 2025. He did not play again until signing for Ajax in December, going on to make just seven appearances for the Dutch club before earning a recall to Japan's World Cup squad, featuring in three of their four matches at the tournament.
Across his Arsenal career, which began with a £19.5m move from Bologna in 2021, Tomiyasu made 84 appearances and missed a combined 435 days through his knee problem and a further 73 through a calf injury, with a further 59 days lost to fitness issues during his brief spell in Amsterdam.
Tomiyasu had appeared close to a return to Italy earlier this summer, with reports suggesting he was on the verge of agreeing a three-year deal with newly-promoted Venezia FC after the Serie A side moved to beat Sassuolo to his signature.
That move has yet to materialise, and with the free agent instead training in the Premier League this week, suitors elsewhere in England and Europe are understood to still be in the picture as he weighs up his next step.