Rosen bento need to be unpacked when heated. Because most bento lids are made of plastic, if you heat them directly without doing anything to the lids, it may lead to deformation of the plastic and even produce chemicals that can affect your health. Therefore, it is recommended to remove the lid when heating the bento. Meanwhile, if the bento box is not removed, the sealed environment may easily explode, causing food damage and injuries. Therefore, when heating Rosen Bento, it is best to remove the packaging and use a microwave oven special plate for heating.