There isnt much of a story really. Takanashi justs goes to work at a family restaurant full of weird and unique co-workers and takes it from there for the rest of the series. However even with the lack of a real story, Working!! makes up for easily with their characters. Even with the lack of plot, a handful of the characters were well done in the sense that they achieve what this anime was ment to do, to make us laugh. There were quite a bit of running gags, but still has more then enough to keep you watching.
For an anime with very minimal plot, it does a very outstanding job in entertaining its viewers and is definitely worth watching.
