This story book is not native Korean. It's a translation of something by Helen Oxenbury. But it translates well to the contemporary Korean cultural mileau, methinks.
It's about this kid's birthday. The title in Korean is 오늘은 내 생일이야. Here's the Korean cover.
The kid goes around getting ingredients for his cake from various animals. The take-away phrase: "갖다 줄게" [I'll bring it.]
My favorite part (i.e. cutest picture) is when they then all get together to make the cake, near the end.
The line at the end of this page: "우리다같이 케이크를 만들자" [Let's all of us together make the cake].