Crows, and especially ravens, often feature in European legends or mythology as portents or harbingers of doom or death, because of their dark plumage, unnerving calls, and tendency to eat carrion. - according to Druid times they're also believed to bring upon new changes (death to one phase of your life and the birth to another)
A version of the three crows is probably based on the three ravens folk tale where three crows plot to devour the corpse of a dead knight. Then they are thwarted by the knight's hawk, hound and mistress.
Three crows are also often implicated in the parliament of crows where three crows preside over a larger number of crows and sit in judgment over the fate of another crow. The verdict sometimes results in a crow being set upon by all the other crows. This behavior and their tendency to show up at battlefields and the scenes of murders may be explain the collective term for crows as being a 'murder of crows'.
Three crows also refers to a tale of three crows (a father, mother and son crow) bothering the king.
The Three Crows (三羽烏) may refer to the group of three go players who are part of the triumvirate of certain eras in go history. These players include Hideyuki Fujisawa, Keizo Suzuki, and Toshiro Yamabe (1940s). Although, since Suzuki died young, he was replaced by Takeo Kajiwara. Hashimoto Utaro, Murashima Yoshinori, and Shinohara Masami (1950s). Fujisawa Hosai, Takagawa Kaku, and Sakata Eio (1960s). Ishida Yoshio, Kato Masao and Takemiya Masaki (Kitani dojo). In Japanese the term is used of triumvirates of other fields as well, e.g. sumo and baseball. In the Kwantung Army of Imperial Japan for instance, the Three Crows refer to the Triumvirate of Army War College 24th class graduate Kenji Doihara, Army War College 28th class graduate Itagaki Seishiro and Army War College 30th class Military Sword Club member Kanji Ishiwara: the main masterminds of the Mukden Incident and the subsequent invasion of China.