[2] Takayama has been considered the key person in the entire history of the Kodo-kai and behind the sixth Yamaguchi-gumi, being kept under close surveillance by the National Police Agency.

[4] The sanctions also targeted Kenichi Shinoda as the leader of the Yamaguchi-gumi, along with several individuals linked to three other transnational organized crime groups, the Brothers' Circle of Russia, the Camorra of Italy, and the Los Zetas of Mexico.

[5] Takayama entered the underworld in his teenage years,[6] and his career as a yakuza officially began at the age of 20 when he joined the Sasaki-gumi, a Yamaguchi-gumi affiliate based in Nagoya.

[9] In 2008, under his dominating influence, the headquarters purged a total of nine "big names" from the syndicate, including Tadamasa Goto as the head of the Goto-gumi, and forced two into temporary suspension, resulting in causing some serious controversies in the entire Yamaguchi-gumi community.

Originally started with just 25 members, the clan grew to an exceedingly powerful, 4,000-member organization within only 26 years, as noted in the National Police Agency's anti-Yamaguchi strategy report distributed in 2009, and this rapid growth, as an "astounding success", was largely attributed to Takayama.

[3] In November 2010, Takayama, as the "de facto leader of the Yamaguchi-gumi",[11] was arrested on suspicion of extorting more than US$400,000 from a businessman in the construction industry.

[12] "If Takayama is successfully prosecuted it will be devastating for the Yamaguchi-gumi, and could even spark a war for control of the organisation," said Jake Adelstein.