Amazon finally updated their product page with the cover of volume 13 and they also included this sleeve with the announcement that the series has reached 3.2 million copies in print circulation! This 3.2 million doesn’t include a restock of volume 12. To this day, you can’t buy a physical copy of volume 12 from a store. It has to be done second hand. So that 3.2 million would probably be higher if they gave volume 12 a restock.
Anyways it’s a great time to be a fan of shinmai and it’s nice to see the series being celebrated in the lead up to the conclusion of the series.