Japan's Prime Minister Shinzo Abe arrived in Tehran on Wednesday, in the first visit by a Japanese premier since the Islamic revolution.
Mr Abe is on a mission to ease tensions between the United States and Iran, hours after Iranian-backed Houthi rebels launched an attack on an airport in Saudi Arabia, injuring 26.
Iranian officials said they wanted Mr Abe to negotiate an easing of oil sanctions from the United States following the visit.
"Japan can help in easing the ongoing tension between Iran and America... As a goodwill gesture, America should either lift the unjust oil sanctions or extend the waivers or suspend them," a senior Iranian official told Reuters.
Shortly after the Japanese premier's plane landed at Tehran's Mehrabad International Airport, he went to meet Iranian President Hassan Rouhani. Mr Abe was greeted by Iran's Foreign Minister Mohammad Javad Zarif.
Later, Mr Abe will meet Iran's Supreme Leader Ayatollah Ali Khamenei.
Japan is one of the few US allies who also has a strong relationship with Iran, making them a potential mediator to de-escalate tensions between the two arch-enemies.
Hours before Mr Abe arrived in Tehran, Iranian-backed Houthi rebels launched a drone attack on Saudi's Abha International Airport, injuring 26, three of which were children.
Wednesday's attack will bring to the forefront tensions between Iran and the United States and Arab nations, which have threatened to boil over into a full-scale conflict in the Middle East in recent months.
The attacks are reminiscent of a Houthi drone strike on Saudi oil pumping institutions and attacks on four shipping tankers in May, both of which are suspected to be ordered by the Iranian regime.
The United States moved 1,500 troops, B-52 bombers and an aircraft carrier to the region, which US officials on Tuesday said put the Iranian threat on "operational pause".
As well as military bluster, Iran has reneged on their promises under the 2015 nuclear deal, which lifted sanctions in exchange for curbed and limited uranium enrichment, citing US breaches of the agreement.
This has led to renewed sanctions, which threaten to further harm Iran's already ailing economy.