The Miyazawa family was brutally murdered on December 30, 2000 in a crime that shocked Japan and began a grim new chapter in the country's criminal history. The killer left many things behind but had still not been identified 22 years later. The investigation is still on going and there is hope one day in the near future DNA technology can find him. My sources- https://en.m.wikipedia.org/wiki/Setagaya_family_murder

https://web.archive.org/web/20151216123931/http://www.japantimes.co.jp/news/2015/12/15/national/crime-legal/relative-murdered-family-claims-tv-asahi-program-misrepresented/#.VnFbiyXLclQ

https://www.tokyoweekender.com/2018/12/5-of-japans-most-famous-unsolved-crimes/

https://www.abc.net.au/news/2019-12-29/the-house-of-horrors-in-setagaya-japan/11771304