If an Italian Citizen passed away in Japan, their death must be registered to Italian authorities as well, even if they held other citizenships.
In order to do so, the following documents need to send to the Consulate:
- Death Certificate (shibo todoke juri shomeisho死亡届受理証明書), apostilled by Japanese Ministry of Foreign Affairs (Information here: http://www.mofa.go.jp/ca/cs/page22e_000416.html)
- Italian passport of the deceased person, either expired or still valid. Please notice that this must be the original, not a copy