Kenneth Francis was a teacher at Widford Lodge Boarding School in Chelmsford in the 1970s.
Francis, of Akasaka in Tokyo, was convicted of 15 counts of indecent assault and two counts of committing an act of gross indecency.
Francis was found guilty of abusing 4 boys all under the age of 16 at the time of the abuse.
The sexual abuse happened at the school and at Francis's then home in Borehamwood between 1972 and 1979, with Francis giving alcohol to some of his victims.
Chelmsford Crown Court heard Francis touched boys' genitals and told one of them: "This is our secret."
He was jailed for 12 years and will serve half in custody and the rest on licence.
Francis must also sign the sex offenders register for life and was made subject of a 12-year Sexual Harm Prevention Order, banning him from contact with any boy under 16.
If you, or a loved one, have been affected by sexual abuse, please do not hesitate to contact our team of experienced lawyers who will be happy to speak to you about whether it may be possible to bring an abuse claim.
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