Police arrested three Chinese people and a Japanese citizen Monday on suspicion of enabling two of the three Chinese to enter Japan by passing them off as children of a Japanese returnee from China, police officials said.
The four suspects are Yang Defang, 38, his Japanese wife Keiko Sonoda, 36, of Adachi Ward, Tokyo, and Yang's 34-year-old brother and 32-year-old sister of Ueda, Nagano Prefecture.
The younger siblings entered Japan in February 1999 under Japanese passports issued after false documents identifying them as children of the returnee were submitted to Japanese authorities the previous year, according to the police.
The siblings continued to live in Japan illegally under false authorization because they are registered as Japanese nationals.
The police said they are questioning the 63-year-old Japanese returnee on a voluntary basis.
He was left behind in China as a child after Japan surrendered in World War II. He returned to Japan with the couple's help in 1994.