Driving the news: The blast took place amid Japanese Prime Minister Fumio Kishida’s visit to the port, according to the Associated Press.
No one was injured in the incident, as per local media.
The explosion reportedly occurred just as the prime minister was set to deliver his speech.
Status report: Kishida was evacuated from the scene unharmed, AP reported. He was at the port campaigning on behalf of his party's candidate, with just days to go for local elections, including a parliamentary bypoll, to be held across the country.
Why it matters: The incident comes just nine months after Shinzo Abe, Kishida's predecessor, was assassinated while delivering a campaign speech.
On the scene: Police apprehended the suspect who has been identified as a young male, as per local media reports.
He was allegedly seen hurling the explosive before being caught by the authorities.
Déjà vu: The incident calls to mind the assassination of former Japanese PM Shinzo Abe in July 2022.
For one, Abe was also out campaigning when he was shot by an attacker in the city of Nara.
The suspect allegedly shot Abe over the latter's ties to a religious group.
Several world leaders, including PM Modi, had expressed their sympathies over the death of Japan's longest-serving prime minister.
(With inputs from Associated Press and NHK TV.)