Fastech 360. Two sets were built in 2005 as a test to figure out how the new SHinkansen should be designed. They had unique cab designs at either end along with emergency air brakes at the top of each car that earned them the nickname "Cat-eared Shinkansen". After testing they were scrapped in 2008 and the data was used to develop the E5 series.
https://www.youtube.com/watch?v=2GNTfE6d7VM 