Requirements:

Transport of Human Remains

1. Certified copy of Death certificate
2. Burial/Transit Permit
3. Passport of decedent
4. Embalmer's affidavit
5. Letter of non-contagious disease
6. Funeral home letter stating: 1) only remains are inside the casket 2) flight itinerary; 3) consignee's name, address, and telephone number; 4) Name, age and sex of deceased
7. Sealer casket

Transport of Cremated Remains

1. Certified copies of Death Certificate (2)
2. Cremation Certificate
3. Passport of deceased
4. Consular fee $23.00

Consulates: http://www.state.gov/s/cpr/rls/fco/164204.htm#japan

Embassy: http://www.embjapan.org/