[4] In 1960, the Yamaguchi Gumi was involved in a deadly gang war in which Yoshinori Watanabe proved himself to be violent but effective mediator in resolving disputes.
[6] During the first few years of being the 5th Generation Kumicho (Don, Chairman, or Godfather), Yoshinori Watanabe made very few changes to the Yamaguchi Gumi Yakuza organization.
[4] In order to make the Yamaguchi Gumi into a powerhouse of organized crime nationwide, Yoshinori Watanabe strengthened bonds with allies and formed new ones with rivals.
[4] By the year 2000, Yoshinori Watanabe had increased the size of the Yamaguchi Gumi by 5,000 gangsters and maintained offices in 43 of the 47 Japanese prefectures.
"[7][8] It was unscathed by the 1995 earthquake,[8] and under Watanabe's order the Yamaguchi-gumi claimed to have given away 1 billion yen of goods and 20,000 free lunches to survivors, although there were accusations that the motives were not wholly altruistic.
[5][8] Police estimated that he received US$1 million a month from his aides in honoraria,[8] and the full-time members of Yamaguchi-gumi had increased by one-third to 16,500 a decade after Watanabe took over.
[4] Kazuo Taoka's widowed wife acted as Kumicho until she named Masahisa Takenaka to lead the Yamaguchi Gumi in 1984.
In 1989, Yoshinori Watanabe took the position of 5th Generation Kumicho of Yamaguchi Gumi and ended nearly ten years of violent power struggle within the largest yakuza organization.
[15] Yoshinori Watanabe's huge ceremony to commemorate accession was held at a local shrine and infused traditional and feudal aspects of the yakuza society.
It is believed that the Yoshinori Watanabe was the largest beneficiary of the earthquake because of his organization's extensive links in the Kobe construction industry.