Question: What research and development unit allegedly involved ex-soldier Yasuji Kaneko?
Context: The Vigário Geral Massacre ("" in Portuguese) occurred on August 29, 1993 at the "favela of" Vigário Geral, located in the north of Rio de Janeiro city.  A death squad composed of Rio Military Police was responsible for carrying out this act of violence.  The group supposedly did so out of revenge for the killing of four police officers two days prior, who were allegedly involved in the extortion of drug traffickers.  After arriving to the "favela" of Vigário Geral on August 29, 1993, the squad spent two hours traveling around wearing hoods over their heads and sporadically shooting at local residents, leaving 21 innocent people dead.  "Among the deceased were seven men playing cards in a bar and eight members of a family, including a 15-year-old girl, killed inside their home."  After the federal and Rio de Janeiro state governments commenced a series of official investigations that year, charges were brought against thirty three people: twenty-eight military policemen who were believed to belong to infamous death squad ""Cavalos Corredores"" (the "Galloping Horses"), three civil policemen and two civilian employees of the civil police.  By 1998, the number of people charged increased to the total of fifty-two, but only two had actually been convicted thus far.  Six policeman had been convicted as of 2003, yet according to a BBC newspaper published in August, only two were actually in prison as the other four were released with the expiration of the time periods for their appeal hearings. The Nine Trey Gangsters (also referred to as Nine Trey Gangstas) are a set of the United Blood Nation street gang, the latter of which is a set of the Bloods street gang.  The gang was established in 1993 at the Rikers Island jail complex in New York City, and operates on the East Coast of the United States.  The gang has operated in the U.S. state of Virginia and other states.  It has allegedly been engaged in the sex trafficking of their women and racketeering in Virginia, New York, North Carolina, Maryland and other areas.  The gang was also allegedly involved in the distribution of illegal drugs, including heroin, cocaine, crack, ecstasy, marijuana and prescription painkillers in these areas.  Further allegations include dealing in counterfeit U.S. currency and using counterfeit currency to "finance wholesale drug purchases". The 1982 Lake Waco Murders refers to the deaths of three teenagers (two females, one male) near Lake Waco in Waco, Texas, in July 1982.  The police investigation and criminal trials that followed the murders lasted for more than a decade and resulted in the execution of one man, David Wayne Spence, as well as life prison sentences for two other men allegedly involved in the crime, Anthony and Gilbert Melendez.  A fourth suspect, Muneer Mohammad Deeb, was eventually let out after spending several years in prison. RBG Resources was a British public-limited firm based in London that was allegedly involved in a serious fraud worth close to £300 million (US$600 million).  RBG Resources made $1.1 billion in sales in 2000.  It was an affiliate of the United States based Allied Deals Inc., which was also involved in the fraud, and resulted in 14 people convicted or pleading guilty to related crimes. Yasuji Kaneko (金子 安次 , Kaneko Yasuji , January 28, 1920 – November 25, 2010) was an ex-soldier of the Imperial Japanese Army, and a former detainee of both Siberian Internment by the Soviet Union during 1945–1950 and Fushun War Criminals Management Centre in China during 1950–1956.  He was known for his extensive war crimes testimony, including his alleged involvement in the Unit 731.  His testimony appeared in the 2001 film "Japanese Devils" and the 2007 film "Iris Chang: The Rape of Nanking" (although he was not involved in the Nanking Massacre).  He was a member of the Association of Returnees from China. Jaybee Niño Manicad Sebastian (born c. 1980 or 1981) is a Filipino inmate interred at the New Bilibid Prison (NBP) who was convicted for kidnap-for-ransom and carjacking in 2009.  He is known for running a prison gang inside the NBP and was allegedly involved in the illegal drug trade within the prison.  On September 28, 2016, Sebastian and two other inmates were injured, while a Chinese drug lord named Tony Co died after being involved in a stabbing incident in NBP Building 14. Unit 731 (Japanese: 731部隊 , Hepburn: Nana-san-ichi Butai ) was a covert biological and chemical warfare research and development unit of the Imperial Japanese Army that undertook lethal human experimentation during the Second Sino-Japanese War (1937–1945) of World War II.  It was responsible for some of the most notorious war crimes carried out by Japan.  Unit 731 was based at the Pingfang district of Harbin, the largest city in the Japanese puppet state of Manchukuo (now Northeast China). The Association of Returnees from China (中国帰還者連絡会 , Chūgoku Kikansha Renraku Kai ) , often abbreviated to Chukiren, was an organization formed on 24 September 1957 following the repatriation to Japan of soldiers from the former Imperial Japanese Army who were interned as war criminals in China's Fushun War Criminals Management Centre, where interns were subjected to intensive indoctrination by the Chinese Communist Party.  While the Chinese government chose to prosecute the top Japanese leadership, it repatriated accused lower-ranking soldiers to Japan.  Once in Japan, they gave testimony about their experience with crimes such as Unit 731, comfort women, and the Nanking Massacre, but often received stringent opposition from Japanese nationalists and militarists, who proclaimed them to be communists or "brainwashed" by the Chinese communist government.  Its members included Yoshio Shinozuka, Yasuji Kaneko, Tadayuki Furumi, and Ken Yuasa; the association was disbanded in 2002. Ruth Beverly Wilson was an American nurse married to alleged spy Jacob Epstein.  Epstein had been wounded in the Spanish Civil War after he volunteered for the International Brigades.  Ruth, who was a nurse, met him while he was recuperating from his injuries.  They were allegedly Soviet intelligence agents, who were stationed in Mexico City during World War II.  They were allegedly involved in the efforts to break Leon Trotsky's killer, Ramón Mercader, out of a Mexican prison.  Wilson's code name in Soviet intelligence and deciphered in the Venona transcripts is "Nona". Edmund Neville (before 1555 – in or after 1620), was an English courtier and peerage claimant, and possible conspirator.  He was allegedly involved in Parry's Plot.
Answer: Unit 731