Seirei-tachi no Rakuen to Risou no Isekai Seikatsu manga summary:

It's the Golden Week, and Yuuta Morizono (Age 25) can't wait to spend the next 11 days staying home and conquering all of his games and manga. After a trip to the supermarket to stock up on food however, he found himself stranded in a wasteland with no sight of human - how is he going to survive with just the food he just bought?