Faster than the speed of... toes? Weary commuters aboard the famed Shinkansen bullet train in Japan may can now end their working day with some on-board relaxation, peeling off their socks and shoes and delving their tired soles into one of two 2.4m vats of warm, bubbling water. Latte and newspaper optional. For 15 minutes, passengers can face a window watching the world flash by.