From the The Mainichi:
NAGOYA (Kyodo) -- In a move to better compete with a rival train operator's famous "seven-minute miracle" for cleaning a bullet train between its arrival and departure, Central Japan Railway Co. will shave off two minutes from its own shinkansen cleaning work, beginning next spring.
https://mainichi.jp/english/articles/20190605/p2g/00m/0bu/060000c?fbclid=IwAR0eP7xFRwO0WbrFoMIn3n3C0d8KoNGuZgb7TnsaXZLVgjFKEjGf1dih_wg