Help Mark badge; badge indicating a hidden disability or medical condition
A badge worn to discreetly signal that the wearer may need assistance due to a non-visible condition, such as an internal disorder, pregnancy, or hearing impairment. Primarily used in Japan.
wasei-eigo (Japanese-coined English), from help mark
If you see someone wearing a Help Mark badge on the train, please offer them your seat.
The Help Mark badge is for letting others know that you have an illness or disability that isn't visible.