I think it is referring to “SL広場” (SL hiroba) which is front area of east entrance of JR Shinbashi station. “SL” stands for Steam Locomotive where there is C11 Japanese steam locomotive in display at front area of east entrance of JR Shinbashi station, which is referred as “SL広場“ which could be among English speaking expatriates in Tokyo refer to as “SL Plaza”…

I agree that many places will start closing between 10– 11 p.m., Tokyo is not 24 hrs. city. There was one small mom and pop type noodle shop right near Shinbashi station which was open 24 hrs. but recently closed. Any places open that late at night which serves meals in Tokyo…, it is possible that you may need to read or speak Japanese to figure things at such establishment…