I saw a picture of the single claiming to be a limited edition in whioch the cover folds out to show a pic of each member.
Since it wasn't exactly saying why that edition was listed as 'limited'...I was wondering..is that booklet thingy the part that makes it special or is this something all versions of the single have?
Weekend, Kurenai and Endless rain all have limited edition which has the booklet you described. Non-limited are like regular 8cm singles: they have only a cover which opens up instead of booklet.
Also kurenai has some shining on it and Endless rain's text is golden instead of regular silver. I wonder if weekend had something special like that in addition to the booklet, can't remember and too lazy to check.
I hope this helped you. If you have anymore questions, don't hesitate to ask \o
I might be able to provide some pics for comparison later today. If I can get a hold of a camera.