Sushi is kept in the refrigerator at night. Because it is cooked food, it can be kept in the refrigerator for one day at most, that is, 24 hours, and it will not work after that. You can eat it when heated, but it's not fresh. Just throw it away after more than 2 days.

if you put it in the freezer, it is ok to put it in the freezer for a week. But it will definitely taste bad when heated.

so it is best to eat it immediately after overnight.