There's a lot of meta jokes about how it's the 10th anniversary. The 4th wall was always flimsy in this show, especially when it came to Akari and her lack of presence, but they seem to ignore it entirely in this entry as the girls all try and come up with a suitable way to spend their 10th anniversary celebration. Then it turns out it was a fake-out and it was actually Akarin's birthday they were celebrating, so I guess Akarin's birthday is canonically also the same day as the anniversary of the series. All your favorite characters are here, and it really is a prettygood celebration of the franchise and what makes it special. It doesn't try to tread any new ground because it's just meant to be a love letter to the series. 7/10 it had a little something for everyone.