KOBE -- The 15-year-old boy who has confessed to murdering two children and assaulting three others here earlier this year will undergo mental treatment at a juvenile medical institution, the Kobe Family Court said Oct. 17.Judge Yasuhiro Igaki said the boy, whose name is being withheld, may have a serious mental disorder that will affect him in the future, and that treatment should be taken at one of the nation's four facilities equipped to give mental or physical support for juveniles, according to the court. The Justice Ministry said later the boy would be taken to Kanto Medical Juvenile Training School, which is located in the western suburb of Fuchu, in western Tokyo.Such minors can be detained until they reach 26 years of age.Family courts rarely disclose the findings of closed-door hearings, but in the last hearing, the judge decided the boy was responsible for the crimes. The judge said the boy is not mentally ill but should be treated because he still tries to justify his actions. He also reportedly said the boy suffers from deeply entrenched sadism related to aggressiveness and an immature sexual impulse.