In the top left Matsumoto avoids the complex variations of the taisha and then plays an ideal move with . Next however is a mistake, according to KataGo. The pro also notices that A, KataGo's alternative, would have been better, even already at .

is probably the reason why wasn't so good. It's an obvious reduction point.

gets a lot of praise by Miyamoto. KataGo too likes the combo here but would first play A.

From to the players play chicken and surround each other. White is the first to defend. The book analyzes thoroughly what happens if breaks out with the top left group.

Instead of surrounding with , KataGo would defend the top at the vital point A. White's vital point in the top right is B but KataGo has a slight preference for moving out with C. White however plays the sharper .

Matsumoto counterattacks at the vital point . KataGo agrees. When continues, Black has another option for , says KataGo.

Black can cut at instead of in the game. Now White has a lot of work to do in the top left while dealing with aji like A.

Miyamoto discusses the cut in the book:

Miyamoto has connecting here, leading to an escape to the center. KG finds this an acceptable variation but thinks Black can do better.

If turns first before playing , White has a tough decision to make. seems to end in disaster (playing out a couple of variations) so it might be better for White to play immediately and sacrifice 3 stones. Still there's a lot of aji in the corner and Black might get sente in the top left.

Miyamoto also discusses . He doesn't like the result up to , where White lives with miai of A and B.

KataGo sees many more variations and basicially prefers the cut for most of them.

Black lets White off the hook in the game, allowing him to live inside while taking territory and sente for himself. When takes sente to play the big point, Miyamoto calls the game extremely close. KataGo thinks Black still leads by 3,5 points.

Miyamoto calls White's settling at the top "brilliant". As we have seen, Black could have countered but decided to keep things peaceful. What's clear is that Shusaku created major complexity to test Matsumoto's strength to the fullest.

Miyamoto calls the light reduction of correct. Again KataGo finds a more aggressive move (see next diagram). is "the only move" in the book but KataGo wants to continue in the center.

KataGo finds this astute "half peep" aiming at the ko of A while simulteanously threatening to separate at B. For White to cover at A would be dame so he should fight again, in Black's sphere of influence.

in the game is quite similar and White seems compelled to defend:

After forcing with in the previous figure and here, returns to defend. This keeps Black ahead. The endgame is near now and Black takes , allowing . Miyamoto questions if Black shouldn't have taken for himself. KataGo has another idea:

at . Next Black can play A and take territory while attacking. Black can now also look forward to some central territory.

Both apply mutual damage but it's White who gradually reduces the gap this way.

Miyamoto calls "essential" to prevent Black's central territory. KataGo values the endgame diagonal at A at least on par.

However is a mistake per KataGo's analysis.

and force from the outside before living.

KataGo doesn't think is forcing and suggests the following counter:

Rather than connecting, it cuts off White's lifeline to the bottom while reducing the corner. White can indeed push through as Miyamoto argues, so that if Black blocks at A, White can capture two cutting stones at B. But Black can throw these away! He can reinforce at and the focus then lies on White's corner with moves like C and D which White can't have both.

In the game, Black is playing on neutral points while White takes the large point on the side as kikashi. This is a big difference.

and reduce the center to an almost neutral area.

is a small loss and should have been at but Black gets another chance.

Finally, when links up his stones without any profit, takes a small lead, which Shusaku will convert into a 2 point victory.

There are many comments in the book about the endgame and we could spend more analysis on those with KataGo's view, but this is enough.

Conclusion

Miyamoto Sensei concludes that Matsumoto Inseki has made no mistakes but Shusaku played brilliantly, moving into the lead imperceptibly, the key moment being the skillful settling of his group in the top right.

KataGo indeed doesn't reveal any big point losing mistakes by Black but there are some points in the game where he could have counterattacked to maintain or regain the lead, most notably the cut at , which the book dismissed, and the clever play at B115, sacrificing the cutting stones in a flexible manner.

The steady graph, with oscillations of at most 2-3 points, confirms Miyamoto's assessment of a "masterpiece".