TOKYO— In movies about the yakuza, the Japanese mafia, and in the real concrete jungles of the Japanese underworld, there is what might be called The Circle of Death. Every assassination tends to bring another, and in the past, and possibly in the present, funerals to mourn the dead often end up as cues for more bloodshed.

Police are investigating the possibility that the attempted murder on Tuesday of the leader of Japan’s newest yakuza group, Ninkyo Yamaguchi-gumi (The Chivalrous Yamaguchi-gumi) may have been connected to the funeral of another yakuza boss that same day.

Before dawn on Sept. 12, Shigeo Nishiguchi (aged 88), the sosai (supreme leader) of Japan’s second-largest organized crime group, the Sumiyoshi-kai, passed away. He wasn’t the only yakuza to die that day, but at least he was lucky enough to die of natural causes.