Sega Online has a Japan only 'random item draw' thing that you can enter if you live there in 2019. By sending in 500 yen, you would recieve in the mail an item from among a prize pack selection. It included pins, keychains, these two bags, and post cards.
These are thick quality paper or matte plastic bags with fabric or ribbon handles that are made to be used again and again. The art for the left bag seems to be a repeating fleur-de-lis shape for the background, with characters from the "Watercolor style texture summer set" around a pink patch with "Sonic the Hedgehog" written in it. The right bag has a scattering of all the character art from the set.

These two bags have the lowest probability of all of the items that you could get from the grab style buying. So, they will likely end up being uncommon.