Enda Kenny says he'll remember Shinzo Abe as a peace-loving, outgoing supporter of smaller countries like Ireland.
The former Japanese Prime Minister was shot while making a speech in the western city of Nara earlier today and died from his injuries.
A man in his 40s been taken into custody in relation to the assassination.
Enda Kenny says Mr Abe was a great supporter of Ireland and the EU:
"I think he really expressed himself [and was] interested in Ireland as a small country having made the progress that it has made and use his connections with the European Union to be a part of that. He wanted to do with Europe, what he was beginning to do with Ireland; to share the values that we have open trade, a peace loving country and respect for the rule of law. That was his measure."
Irish freelance journalist Brian Gaynor, who's based in Japan, has the latest on a possible motive:
"Apparently he has said, or the police have said, he was frustrated with Mr. Abe but it wasn't anything particularly political he had against Mr. Abe. Apparently he was a member between 2002 and 2005 of the Japanese Maritime Self Defense Forces which would be the Japanese equivalent of the Navy."