The parents of a 14-year-old boy who was killed in what a family court deemed to have been a one-on-one fight with another boy are to file a damages suit next week against the state and Ibaraki Prefecture, claiming the investigation was unfair, it was learned Friday.

They filed a 100 million yen damages suit Thursday with the Tokyo District Court against the other boy.

The lawsuits are aimed at shedding more light on the case. They are also likely to provide another topic for debate on the opaque juvenile crime investigation process in Japan as they come at a time when revisions to the Juvenile Law are being considered.