Tel - ++81 (0) 236-79-2311
Fax - ++81 (0) 236-79-2316
A cheaper option is to catch a night bus (12000 yen return) but this means 7 hours on a coach.
Take the bullet train (21/2 hours) from Tokyo to Yamagata from where it is a 40 minute bus ride up to the mountain (18000 yen return). Alternatively, get the Oou line to Kaminoyama which is 40 mins away.