Japan Today has run a story that implicates a 60-year-old construction company president, Hiromi Ogawa. He drove the car to the scene of the assassination, but denies he knew Shiroo would kill Ito.
However, a long comment on the story by T_bagger, goes further than any news outlet has yet gone (at least in English: I've got no idea what the Japanese-language papers are printing). He says:
Ogawa-san ran a construction company which was basically a front for the mob boss Shiroo's Suishin Kai. They actually were a construction company but did money laundering and also were in debt to Suishin Kai. Shiroo had manipulated Ogawa-sans company so he was perpetually in debt to Suishin Kai.
Suishin Kai was getting squeezed by rival gangs and their payments to their overlords (Yamaguchi Gumi) were scraping bottom.
Nagasaki City has a loan program for small and medium size companies which was introduced after the bubble to help recovery. Ogawa-san was instructed to apply for loans by Shiroo-san which would have ended up in Suishin Kai accounts.
Nagasaki City denied the loans a few times for the reason that Ogawa was a criminal front. The matter finally made its way up to mayor Ito after threats fron Suishin Kai.
Yamaguchi-Gumi was putting heavy pressure on Suishin Kai and Shiroo-san was frustrated after ordering his underlings to kill mayor Ito. He finally took matters in his own hands. Ogawa-san was comliant but probaby under duress from Shiroo-san.
Long post, but basically this kind of dealing goes on unnoticed. Murders are rare because the threats usually are effective. After the Nagasaki case the abused will act without reprehension [blame] when these kind of threats arise.
I'm not sure what the last sentence means: whether the criminal gangs will act 'without blame' or the people they 'abuse' will. If he means the latter, then I'm not so sure I agree. It seems to me that the police and politicians are powerless to do anything to curb gangs in Japan. Part of the problem, from my point of view, is that the press is not allowed to operate effectively, and to investigate fully cooperation between public officials and gangs.
(I've tidied T_bagger's text up a bit to make it more comprehensible.)
The Japan Times has run a story that implicates another man, Masaki Yamashita, aged "in his 20s". Yamashita, also, is accused of driving the car (they both can't be the driver).
"Yamashita is suspected of monitoring Ito's movements at places other than his election campaign office."
"Police said Yamashita told them he was a lookout but did not think Shiroo would kill Ito."
"Police believe both Yamashita and Ogawa knew Shiroo was planning to murder the mayor and said they will question the two suspects about the shooting."