Played with a toy train following a black line. https://t.co/bvuSa0kIJp pic.twitter.com/T7WSEHmbcw

— Yoshiyuki Nakai (@yoshiyukinakai) January 27, 2019

The toy train is able to climb a gentle slope and stop at the end of the black line pic.twitter.com/lpXSsdF9r8

— Yoshiyuki Nakai (@yoshiyukinakai) January 30, 2019