The reigning Japanese Rugby League One champions said Marx would not be in their squad for the upcoming season that kicks off in December but added that he would return before his contract expires in May 2025.
Through a video message, the 29-year-old Springbok said "unfortunately, due to my injury I won't be able to play next season but I will be back for the following season, hopefully."
"Please carry on your amazing support towards the team. I think the team and everybody really appreciate it," he added.
Marx, was forced to leave the Springboks' World Cup-winning squad after only one game in France following an injury to his knee during training.
He was forced out of the World Cup when he went down in training after "having his knee caught in contact" before the Springboks' pool stage game against Romania.
Head coach Jacques Nienaber opted against calling up a direct replacement, with back-rowers Deon Fourie and Marco van Staden offering cover for Marx, as well as Bongi Mbonambi.
Marx was instead replaced by fly half Handre Pollard, who kicked four first-half penalties as South Africa beat New Zealand 12-11 in the final in Paris on Saturday, clinching their historic fourth title.
Prior to Saturday's final, South Africa and New Zealand had won the World Cup an equal three times.