First thing to do when you arrive at Japan Expo Sud: going through security checks (more information).
Attention, since last year, the entrance is set at Gate E at Marseille Chanot, where you'll find the security checks in the Palais de l'Europe. You must go through there before joining the line corresponding to your ticket or leading to the cash desks.
Have a look at the new access map on this page.
Before going to Japan Expo Sud, read the list of forbidden and authorized items to avoid having your accessories confiscated.