As for the cost, I just went to that store in Juchuan last week and asked. The annual card is more than 700 (but the member consultant will tell you that it is around 600 when there is an activity, and they can tell you soon when there is an activity).
Both the monthly card and the season card fee are required, because it is not cost-effective.
If you are interested, you can go to the store to have a look and experience. You can take a look while they are in class and find out what they feel. The member consultant is very enthusiastic and patient ~