Hotels sold out on 30th of July in Sendai

Hi! We're choosing between Osaka and Sendai from july 30th - 2th august and from there go to either one and stay for another three nights. I've discovered that from this day july 30th - 31th in Sendai almost all hotels are sold out?! Does anyone know what's going on, is there any event planned causing this? Any other date is available in the whole summer.
There are some smaller cheaper hotels available of course but the better hotels are all sold out.
Have done some googling but couldn't find anything more than a little football game between Sendai and some other team.

It's the Suzume Odori festival.

Thanks! It makes sense if this is the event causing this.
Athough I'm not able to find anything about Suzume Odori festival being in end of july. Rather in may.
Here from 2014 in may http://en.japantravel.com/miyagi/aoba-festival-suzume-odori/13084

Oh well, I hope hotels in sendai haven't released all of their available rooms or plenty of people will cancel their bookings so I can book mine ;)

http://www.suzume-odori.com/

See the dates? ７月30日31日.

July 30 and 31

This link is about the Aoba festival, in which the Suzume Odori dance is also performed. http://www.suzume-odori.com/

Thanks a lot :)