Let's first examine two typical patterns in which Under the Stones tesuji may appear:

Square Four pattern

Can black save this group? Clearly black 'a' would not work, white 'b' can destroy the second eye easily. What else?

Black blocks the other side. is a typical tesuji to create a false eye by squeezing. However, black won't be that cooperative......

is the correct move.

completes the Under the Stones tesuji, creating a second eye for the group.

Twisted Four pattern

Again, black is to save this group.

is the only starting point. But is incorrect. and combination successfully creates a false eye in the corner to kill the black group.

is the key point to create a Twisted Four shape first, after ......

captures back to form a second eye for the group.

As shown, these are rather practical shapes so it is possible to get these in real games. In the next article, we will review a few professional games in which this tesuji occurred.

Professional Game 1

This is a famous game by Takemiya Masaki, known for this 'Cosmic Style'. One may have a glimpse of this style here: The Under the Stones tesuji never materialised in this game. But a little bit extra reading would reach this outcome. The players has been fighting a messy ko since move 104. White finally gave up the ko at move 168 when running out of ko threats. What happens if white 168 connects the ko? Here is the answer:
After this game, Takemiya Masaki went on to capture the Japanese Meijin title. The 5th game in this series was also a thriller:

This is the position when white resigned. Both black groups have 5 liberties and white corner has only 4. Coincidently, there is another Under the Stones shape hidden here, if white were to continue the capturing race.

Of course can play at 'a' instead. But why not another Under the Stones?

Professional Game 2

The final example was from a major international tournament and played by big star Lee Changho.

When Lee Changho was at his top form, his best weapon was his unparalleled yose skill. is a brilliant tesuji. cannot cut at 'a', otherwise white can play and black would crash. is the next tesuji. Black has to play to avoid white saving his stone in sente. If black plays 'b' instead of , white can occupy to destroy several points. Because the game was really close, was a gamble.

Now it is just a matter of formality to create the Under the Stones shape.

What makes this really special is that a ko fight is created eventually. Lee Changho got this ko out of nothing so he won this game easily.