The game 1.sgf is famous. It is supposed to be the game
played by Nikkai against Kashio Rigen while the warlord
Oda Nobunaga watched, the night before his death.

A triple-ko is said to have occurred in this game.
However, no triple ko occurs in the 128 moves of 1.sgf.
Maybe it occurred later that game, or in another game played
the same day?

Sources say about Nobunaga: "On June 21, 1582, his retainer Akechi Mitsuhide
attacked him at Honno Temple; Nobunaga, his eldest son, his bodyguards and
his wakashu, Mori Ranmaru, died."

The date of the death of Nobunaga is 天正10年6月2日, that is
Tenshō 10-6-2, that is 1582-06-21. The evening before then was
Tenshō 10-6-1, that is 1582-06-20, and the 6-1 explains Western
versions with "June 1".

GoGoD has 1582-06-30 as equivalent of Tenshō 10-6-1, a date 10 days
too late, probably dated using the Gregorian calender (which was adopted
first 1582-10-04 (Julian), the next day being 1582-10-15 (Gregorian)).

GoGoD has a slightly different order of the moves, with the exchange
bb,ab at move 123-124, instead of 127-128.
The current version is from Segoe Kensaku's Oshirogo (1978).