Hi There! This site mentions it takes place on the same dates each year, and is an official site for the Yonezawa area. I would bear in mind though that there have been a lot of annual festivals that have been canceled on account of COVID. There is a contact form on that website I linked you to, so you may want to reach out to them and get a confirmation of whether the festival is definitely going ahead this year.
Take care and have a great day!