This is heavily tilted.

The Japanese conviction rate is high, but this is largely in part because the authorities are extremely reluctant to try cases unless they have a slam-dunk case. See https://en.wikipedia.org/wiki/Criminal_justice_system_of_Jap...

  Scholars say the biggest reason for Japan's very high conviction rate is the 
  country's low prosecution rate and the way Japan calculates its conviction rate 
  is different from other countries. According to them, Japanese 
  prosecutors only pursue cases that are likely to result in convictions, and not 
  many others. According to Professor Ryo Ogiso of Chuo University, 
  prosecutors defer prosecution in 60% of the cases they receive, and conclude the 
  remaining 30% or so of cases in summary trials. This summary trial is a trial 
  procedure in which cases involving a fine of 1,000,000 yen or less are examined 
  on the basis of documents submitted by the public prosecutor without a formal 
  trial if there is no objection from the suspect. Only about 8% of cases are 
  actually prosecuted, and this low prosecution rate is the reason for Japan's 
  high conviction rate.

Also worth noting that, when evaluated equally, the US justice system has a similarly high rate:

  According to Bruce Aronson of New York University School of Law, Japan's conviction rate is
  misleading because it is the rate at which defendants admit guilt in the cases they are
  charged with. According to him, if the method of calculating the conviction rate in Japan is
  applied to the United States, the conviction rate of federal defendants in the United States
  in 2018 was also over 99%. According to him, when there is a discussion about Japan, it
  is easy to misunderstand because people quickly rely on broad cultural generalizations and
  stereotypes.

None of which is to say that there aren't serious problems with the Japanese justice system (or the US one, for that matter).