The animation looked shoddy from the start, especially facial expressions, but I thought I would give this Korean anime a chance. It is about two close childhood friends that meet when they are adults and reminisce about the good old times. Or at least, this my interpretation of the vague plot. The reality of the film is that these two adults meet, you get a feeling they are old friends, and then there they are, as children, for the rest of the movie.
Now, the story is something of a childhood fantasy, where the two boys find a magical marble that transposes them into an alternate reality. It doesn't happen all the time, only at random moments that seem to have no connection to what goes on around. Then there are bits of school and personal life that defines the characters. It all ends when one of the boys has to leave for Seoul.
I felt it tried to be a Korean Miyazaki clone, but failed. The animation could have been better, but then again, if the story was good, I could have ignored it. The story was good in principle, too, with the childhood friendship, the mysterious girl (I guess she was a girl) from the fantasy world, the fluffy things, etc. However, it was all fragmented, unclear, like they wanted to make a series and then they collapsed all into a anime movie, with only the relevant bits salvaged for the end product.
Bottom line: If they wanted a masterpiece of atmosphere and animation, they couldn't do it. If they thought they were doing something with a deep plot and emotional story, they failed. The result is somewhat in the middle, not one nor the other, and feels unnatural, broken.