universal mems on Instagram: "The post features a 28-second video demonstrating a space-saving design in a Japanese train compartment, where a cushioned footrest under a table unfolds into an extra seat for passengers like children, overlaid with "Only in Japan" text to highlight efficient engineering. Replies reveal mixed reactions, with Japanese residents claiming they've never encountered this feature despite living in Tokyo or long-term, while others note similar adaptations in crowded trans