From the signing ceremony in January, 2018
An exchange on validification papers of the Convention between Japan and Iceland for the Elimination of Double Taxation with respect to Taxes on Income and the Prevention of Tax Evasion and Avoidance (signed on the 15th of January, 2018) was conducted in Reykjavík on the 1st of October. According to the Convention‘s stipulation, it will come into effect on the 31st of October 2018. See below for further details.
Ministry of Foreign Affairs, Japan
https://www.mofa.go.jp/press/release/press4e_002176.html
Ministry of Finance, Japan
https://www.mof.go.jp/english/tax_policy/tax_conventions/press_release/20181002is.htm