The right arm shown on the right picture is from the expansion set - has splits on the arm to show off O Thunder.
The guns will move forward when the piston behind the arm is pressed.
O Thunder beam parts from the expansion set.
Two types of option hand units included for the original package. The chop-type palm in front is from the expansion set.
Two types of head included in the expansion set: The skeletal Arch-type (left), and the one which is slightly bigger (middle) than the one included for the original package (right).
4 Moby Dick Anchors (with 2 types of heads) included for the expansion set.
Roger Smith's car "Gryphon" is also available from the expansion set only.
The extended display base mounting all the unused parts, and the 4 parts linking The Big O with chains are from the expansion set.
The Big O will be released in late September at 13,440 Yen (inclusive of tax).
Pre-order for the expansion set started since August 11th. Closing date TBA. December release, 6,300 Yen (inclusive of tax).
The Big O is one of my favorite mecha anime actually, so you can say I'm quite tempted to get him as my first Soul of Chogokin. Then again, looking at this introduction, I really feel that the original package is very 肉酸 - stingy. ^^;
There are so many good stuff that are available only in the expansion set. At such a high price, I was expecting O Thunder to be in before seeing the Tamashii Web Shop announcement of the expansion set. The beam parts may be extra, but even Moby Dick Anchors, the very "basic" weapon The Big O uses a lot in the anime are only available in the expansion set.
And it's not enough too ^^; The big guy has anchor slot in every sharp edge of his waist (about 12 in total I believe), and only 4 are included. ^^;
As a matter of fact, one shouldn't call it "expansion" set anymore, but "missing" set instead.
The final weapon of The Big O in the anime, "The Big O" is neither included in the original package nor the expansion set. ^^; Maybe a second expansion set is coming? along with his underground transport train? That's going to put a big O on your face for a whole day if you're a fan XD
All images from Gigazine.