tonaki became the oldest living man in japan on 20 september 1991, after 108-year-old gihei oka's death and also the oldest living japanese man overall, later on 16 february 1992 after the 109 years, 13 days old russo-japanese war veteran mamoru eto's death, as eto who was just 4 days younger than oka emigrated to the united states, and later on 30 october 1994 only the second japanese man who became a supercentenarian, after eiju tsuru who died on 11 january 1990, just 24 days before his 111th birthday, although shigechiyo izumi who died on 21 february 1986 was still believed to have been aged 120 years, 237 days and denzo ishizaki claimed to have been ten days older than tonaki, as his birth register which showed a birth year of 1886 rather than 1884 was claimed to have been delayed by two years.