This is another creation by Naoki Inaba, but as opposed to
Island which has a very simple, elegant and intuitive rule, the rules for this one is notoriously sophisticated and it takes a huge amount of time and consideration to devise a not-too-difficult-to-understand format of presentation.
Firstly let's go straight to the source page of the Naoki Inaba site:
http://inabapuzzle.com/honkaku/tona.htmlThe rules translator wrote:
Lines are drawn connecting all the cells. [forming a single connected network]
The complete diagram represents how a tournament occurs.
The three different shapes represent different types of participants.
The Kanji character [translating as "superior"] represents the tournament victory.
Black circles represent a match between two participants.
[The participants and victory symbols have lines in one direction. The black circles have lines in 3 directions. Cells with no symbol have lines in 2 directions.]
The number in a shape is the quantity of matches won by that participant.
The winner of each match continues to a later stage of the tournament. There are no matches which result in draws.
[The winner of each match is determined in a fashion similar to rock-paper-scissors. Square beats Circle. Circle beats Triangle. Triangle beats Square.]
This is the image of an example puzzle (with answer):
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