Just hours after his decisive election win, Moon Jae-in was sworn into office, marking the beginning of his term as South Korea's 19th president.
And it has been straight down to business.
President Moon has wasted no time in addressing what is arguably his country's biggest threat, neighbouring North Korea's expanding nuclear program.
In a speech at the National Assembly, Mr Moon has pledged to work for peace on the Korean Peninsula.
"I will resolve the issue of the national-security crisis as quickly as possible. I will do my best in all directions for peace on the Korean Peninsula. If needed, I will fly to Washington right away. I will visit Beijing and Tokyo, and, if it becomes possible, I will also go to Pyongyang. I will do everything I can to firmly establish peace on the Korean Peninsula."
North Korea's increasingly aggressive nuclear ambitions have sharply increased tensions between the United States and China.
The United States recently deployed a missile-defence system, known as THAAD, in South Korea.
That move had angered China, which says the system's powerful radars will let the United States spy on China's military operations.
President Moon had previously questioned the US move, prompting some to speculate his election win could strain diplomatic relations between the two countries.
But Mr Moon is promising to ease tensions all around, pledging to negotiate with both the United States, South Korea's closest ally, and China, its leading trading partner.
"I will further strengthen the South Korea-US alliance. On the other hand, I will seriously negotiate with the US and China over the issue of THAAD. Solid national security comes from strong national-defence power. I will make efforts to step up our self-defence powers. I will also devise a basis for resolving North Korean nuclear issues."
The United States maintains its alliance with South Korea is strong.
In a phone call congratulating Mr Moon on his election win, US president Donald Trump agreed to cooperate with the country over North Korea's increasingly aggressive nuclear ambition.
President Trump acknowledged it was a difficult problem but insisted it could be resolved.
China, too, has renewed its offer to help diffuse tensions.
Chinese foreign ministry spokesman Geng Shuang congratulated Mr Moon on his election win and said China is willing to work with the new president.
He also assured China would help negotiate a peaceful settlement of the nuclear issue, but expressed hope South Korea would recognise his country's concerns over THAAD.
"China's position on the issue of THAAD is clear and consistent. We hope South Korea can pay high attention to China's concerns and handle the relevant issue in a proper way."
President Moon's victory marks a major political shift for South Korea, not only in regard to geopolitical relations but also within the country.
He must try to mend a country bruised by a corruption scandal that led to the impeachment of former president Park Geun-Hye.
Supporters of Mr Moon in the South Korean capital Seoul say they are hopeful his rule will mark a new era for the country.
"I feel like I'm witnessing a new page in history, so I'm very moved."
This man was a protester who helped pressure the former president out of office.
"All those nights we spent braving cold winds, keeping vigil in Gwanghwamun Square, finally lead to something. We should all share this joy together."
Mr Moon won comfortably with 41 per cent of the votes, far ahead of his closest rival.
But data from an exit poll conducted by South Korea's top three television networks indicates an ideological and generational divide in the country of 51 million people.
The data shows he won most of the votes cast by those under age 50 but more traditional rival Hong Joon-pyo won significant support among older voters.
Still, among the new president's many promises after barely a day in office is to unify South Korea.
