On 27 July, the 50th anniversary of the end of the Korean War, South Korean veterans will be honoured for their patriotism and sacrifice in religious services and war ceremonies.
But in Seoul, there is one war veteran who will spend the day quietly, alone in his little attic room in the south of the city.
Seventy-year-old Park Jong-lin did not fight to repel communism like the others.
Park Jong-lin: "I could have gotten out in 20 years if I decided to drop my Communist beliefs"
In fact, he did the opposite - he served in the North Korean army fighting against the "imperialist American aggressors" and their South Korean allies.
"I was originally from the area which is now North Korea, and it was only natural for me to join the North Korean army when I was 18," said Mr Park.
"The toughest battle during the war was when we had advanced far into enemy territory.
"I was in a man-to-man combat situation with a South Korean soldier, and we literally rolled down a 600 metre mountain throwing punches at each other. When we reached the bottom, we both fainted in exhaustion," he said.
After the fighting ended in 1953 - a formal peace treaty was never signed, meaning the two Koreas are still technically at war - Mr Park lived with his family in the North Korean capital, Pyongyang.
Then in 1959 he was sent on an espionage mission into Seoul that would change his life forever.
"My job in South Korea was to help a left-wing politician win the elections and to arouse pro-North Korean sentiments," he said.
"I was a messenger to teach the North Korean communist ideology to the people in the South."
Prisoner of conscience
But that mission came to an end six months into his stay. He was arrested for spying and sentenced for breaking South Korea's national security law.
Mr Park had to spend most of his life in South Korea behind bars, in six different prisons.
"I could have gotten out in just 20 years if I declared to drop my communist beliefs, but my conscience simply wouldn't let me.
"How can one change his ideology and faith by force? It only made me more stubborn and more dedicated in believing North Korea's socialism," he said.
His ideological dedication gave him another 15 years in jail, until he was finally pardoned on Christmas Eve 1994, after a total of 35 years behind bars.
Park Jong-lin has been trying to return to the North ever since.
His big chance came in September 2000, when the Seoul Government decided to repatriate spies like Mr Park as a good will gesture, after the historic inter-Korean summit.
Mr Park tries to keep in touch with home by surfing the net
When the announcement was made of the 63 spies set to return to North Korea, Mr Park fell into shock.
"I couldn't find my name on the list," he said.
"Later I found there had been some mistake in the government's paperwork. The policy was to send back only former spies who refused to give up their communist beliefs. For some reason I was considered as a fully converted South Korean.
"I protested, saying I was a former spy too - and still a communist sympathiser - but it was too late."
For the time being, Mr Park has to continue to live alone in Seoul, away from his family.
He tries to keep in touch with home by surfing the internet and looking for any news about North Korea.
"Now my only hope for the future is unification of the Koreas," he said.
"But if I had to mention a personal wish, it's simply a chance to return to Pyongyang, the home of my family and the birthplace of my ideological beliefs."