Gamushiro Stacking

Gamushiro Stacking (ガムシロ積み) is a T-Spin opener created by Mr. Goods. It is a Triple Double Attack opener. In the first bag, only the J piece is required before the S. If the mirrored setup is considered, it is always possible to stack the first bag. After the T-Spin Triple from the second bag, it may lead to a Perfect Clear opportunity or other continuations.

First Bag setup
You only need the J piece before S (L before Z in the mirrored setup). The L piece is kept on hold as it will be used along with the second bag.

Here is the first bag with all 7 pieces:

Second Bag
The second bag is always placed in one of these ways. The first 2 ways are the most desirable ways. The first 4 ways can result in a Perfect Clear.

Third Bag (Perfect Clear)
In the case of the first 4 forms mentioned, you can get a Perfect Clear after 8 total lines.


 * L → O (99.09% PC rate, 63 minimal solutions)


 * J → O (96.94% PC rate, 25 minimal solutions)


 * S → O (86.59% PC rate, 20 minimal solutions)

Form A1 and A2 (L → O)

 * T-Spin Triple


 * Imperial Cross


 * Center 4-wide

Form B (J → O)

 * Nil-cross


 * Trinity

Form D (O → L)

 * T-Spin Triple: In the third bag, the O piece must come before Z and S before J.


 * Double Triple Cannon: In the third bag, the J piece must come before S and Z before O. In the fourth bag, you can mostly stack the below. It will fail if you get J before T, S and O. It also requires a late T.


 * Double Triple Cannon 2: The third and fourth bags are stacked the same way, except that the T piece comes early in the fourth bag. Unlike the DT Cannon continuation, you can always stack the fourth bag, as long as you get the T piece early.

Perfect Clear after 10 or 14 lines

 * 10-line Perfect Clear (63.73% PC rate, 24 minimal solutions): You can use this continuation from Form A or C. There are quite some dependencies in the third bag, namely S before J, O before Z then I, or in the case of Form C, O and Z before L and I.


 * 14-line Perfect Clear (100.00% PC rate, 115 minimal solutions): In the fourth bag, only S must come before Z. The I, J, L and O pieces can be placed in any order. The solutions are the same as Riviclia's Pelican.