https://www.sbcr.jp/product/4815619657/
As expected Haruhime and Wiene are on the cover. The synopsis says the newly written SS is about Bell and Ryuu going to the 37th floor again.
I think they are going there to retrieve the bodies they found before. This new SS will probably take place after the war game like the newly written ones from the SS compilation volumes. Bell is Lv5 and Ryuu is Lv6 now so should be easy for them to be in the 37th floor compared to last time.
If Bell is going to 37th floor again, then he will be able to see all of the Lower Floors unlike last time. Maybe we will have info on what the rest of the Lower Floors look like.