Kazuo Taoka was the third boss of the Kobe-based Yamaguchi-gumi, who made the family into by far the biggest yakuza family in Japan. When he died of natural causes in 1981, then wakagashira (underboss) Kenichi Yamamoto was in prison and the other top lieutenants decided to wait for his release. However, in early 1982, Yamamoto suddenly died of liver failure. After his death, the top lieutenants could not immediately elect a boss, and they temporarily chose Hiroshi Yamamoto as acting boss and Masahisa Takenaka as wakagashira.
The situation that led to the war began when Hiroshi Yamamoto broke from the Yamaguchi-gumi along with 18 lieutenants and 3,000 other members to form his own organization, the Ichiwa-kai. The split stemmed from professional jealousy: Yamamoto had been seen as a contender for the role of kumicho, or supreme godfather, in the Yamaguchi-gumi, and was unhappy when a rival, Masahisa Takenaka, was elected to the position by other members, and most importantly by Fumiko Taoka, widow of Kazuo Taoka.
On January 26, 1985, Yamamoto sent a team of hitmen to Takenaka's girlfriend's home in Suita. While waiting for an elevator, Takenaka, underboss Katsumasa Nakayma and one other member of the family was shot dead, sparking a bloody nationwide conflict that came to be known as the Yama–Ichi War. The enraged Yamaguchi-gumi and its newly chosen acting boss Kazuo Nakanishi and wakagashira Yoshinori Watanabe vowed to wipe out the Ichiwa-kai in revenge.
In the years that followed, 36 gangsters were killed and many more were seriously wounded in an estimated 220 gun battles. At the time, local newspapers carried daily "scorecards" with the latest body counts on both sides.
The war continued for several years, and the Yamaguchi-gumi eventually prevailed. It proved to be a Pyrrhic victory however, as many of the gang's members, including Masahisa Takenaka's high-ranking brother Masashi, were arrested in the ensuing police crackdowns. Realizing they were outnumbered and outgunned, many Ichiwa-kai members sought police protection. With the help of a neutral Tokyo gang, the Inagawa-kai, a peace accord was finally brokered under which the remaining Ichiwa-kai defectors were allowed to rejoin the Yamaguchi-gumi.
- Yakuza: Japan's Criminal Underworld ,David E. Kaplan, 2003
- TOPPAMONO: Outlaw. Radical. Suspect. My Life in Japan's Underworld