The former prime minister of Japan will arrive in Wales to campaign against the planned £8 billion Wylfa Newydd nuclear plant.
Naoto Kan will speak at the Senedd then travel to Anglesey to urge residents to fight against the proposed nuclear power station.
Kan was prime minister at the time the Fukushima power plant in Japan was hit by a tsunami, causing radiation leaks.
The disaster led to his resignation and he's been an anti-nuclear campaigner ever since.
He's expected to host a public meeting with members of the local authority, asking them to turn their backs on the proposals.
But Anglesey council say the new plant could create thousands of jobs on the island.
The public were asked to give their views on the proposals in a consultation launched in September 2014.