Jap shares surged at Thursday's open after Washington and Tehran reached a preliminary agreement to halt hostilities and restore passage through the Strait of Hormuz.
The Nikkei 225 jumped 261.5 points or 0.4% to open at 70,163.71.
The accord was confirmed by a US official as having taken effect, though it remained uncertain whether Iran had immediately moved to fully reopen the waterway.
Elsewhere, newly installed Federal Reserve Chair Kevin Warsh used his inaugural press conference to sidestep questions on the timing of future rate moves, instead stressing that inflation has persistently run above the central bank's 2% threshold.
Warsh reaffirmed the Fed's resolve to bring prices back under control, offering no clear signals on what direction policy would take next.