Listed as an approved vendor in Iran by NIOEC, NPC, POGC, NIGC and IOOC.
"Japanese traders including Marubeni Corp and Sumitomo Corp that stopped buying Iranian oil during western sanctions are looking to resume imports, potentially by year-end, industry sources said. Conservative Japanese firms have so far held off taking Iranian crude due to a lack of internationally acceptable insurance coverage, but are looking at ways of using cover provided by the Japanese government, the sources said. The traders seeking to restart purchases together imported around 50,000 barrels per day (bpd) of Iranian oil before sanctions were imposed and renewed purchases would give a boost to Tehran's aim of increasing its exports to 4 million bpd..." (Reuters, "Some Japan trading houses eye resuming Iran oil imports-sources," 10/19/2016).
Sumitomo Corporation lists an office in Tehran. Its subsidiary, Sumitomo Electric, lists a past Major Power Transmission Line Installation Project in Iran.