A team of investigators from five prefectural police forces arrested three people Thursday on suspicion of illegally accessing computer networks by using other people's passwords without permission.
The three arrested were identified as Yasuharu Miyamoto, 39, a self-employed man from the city of Hiroshima, Shunsuke Oba, 23, a student from the Tokyo suburb of Hachioji, and Junko Kato, 42, a corporate worker from Nagoya.
The arrests were the first made under a law enacted in February that prohibits the accessing of computer networks with stolen or borrowed IDs or passwords.
Police suspect Miyamoto used the password of a student at a state-run university in the Chugoku region without the student's permission to access the home page of another student on July 28.
Miyamoto was quoted by investigators as saying, "I wanted to peek into others' privacy."
Oba and Kato allegedly illegally accessed a home page for a tourism association in Yuzawa, Niigata Prefecture, in August by using the page caretaker's password.
Miyamoto, who played the leading role, taught a group of about 10 people, including Oba and Kato, how to illegally access computer networks, according to the team, made up of investigators from the Aichi, Miyagi, Akita, Hiroshima and Tokyo police forces.
The suspects reportedly became acquainted via an Internet bulletin board set up by Miyamoto.
The joint investigative team raided 12 sites Thursday in connection with the hacking incidents and questioned two others of the group -- a 29-year-old male shop clerk from the city of Natori, Miyagi Prefecture, and a 25-year-old male corporate worker from the city of Honjo, Akita Prefecture.
Both are suspected of having illegally accessed a major provider based in Tokyo.