Book Off - Discount day for women?

When i first visited Book Off in Akihabara in Tokyo, they had a tiny discount going, i dont remember if they called it Ladies Day or Girls Day or Womens Day or something else.

I just would like to know, on which day, they have this "discount"?
Is it once a week on a certain day? Or Monthly?
Is it only in Akihabara or also in other places ?

Thank you.

Bookoff In each store, seems certain that the store manager can be determined.
It seems Ladies Day was held on Wednesday in Akihabara, but do not know whether there even now.
Because it was sale of BL, it might have to Ladies Day.
Shin nakano shop also seems there is a case in which Women's Day is opened.

Ladies' Day at Bookoff Akihabara is every Wednesdays, I don't know it's still goes on or not. Only available there, not available at the other Boofoff stores(some stores may do or not).