Productive and driven, he was a model army officer, but he had a secret: he was in a gay sexual relationship with a fellow soldier -- a crime under South Korea's military law.
He kept his sexuality hidden from everyone, including friends and family, only meeting his lover off-base and after work.
Same-sex acts are legal for South Korean civilians, although homosexual people live largely under the radar as it remains a conservative society, influenced by evangelical Christianity.
But the South Korean military classes openly gay men in its ranks as having "special needs" and campaigners say it actively pursues soldiers who have consensual same-sex intercourse with each other.
"I worked very hard as an officer, but none of that mattered when I became a suspect," the 27-year-old, who asked for anonymity, told AFP.
"There were days when I just wanted to die," he added, explaining that he was caught after authorities discovered his messages on his partner's phone.
He faced a criminal conviction and a possible forced outing to his parents, whom he had hoped would never find out the truth about his homosexuality, describing them as "conservative, devout Christians".
South Korea has a conscript army to defend itself against the nuclear-armed North, with all able-bodied male citizens obliged to serve for nearly two years.
Doing so is seen as a patriotic duty, and failure to complete service can bring enduring stigma that affects social standing, employment prospects and more.
South Korea is also the world's only advanced economy to make consensual gay sex between soldiers a crime under military rules. Under clause 92.6 of its criminal code, known as the military sodomy law, soldiers can be jailed for two years with labour if convicted at a court-martial.
For homosexual men this can mean having to live a double life.
- 'Military witch-hunt' -
The officer was among 22 soldiers arrested during a 2017 inquiry into homosexual activity in the army.
He was luckier than most in his position: he was charged during his last month of service, so his case was transferred to a civilian court and he was later acquitted.
It was the first time a soldier charged under the military sodomy law had been found not guilty.
And while he has begun a civilian life with a new job, and thus far avoided his family finding out any details of his sexual orientation -- prosecutors have since appealed, leaving him in a legal and social limbo as he awaits the next hearing.
He said: "It is as if my entire existence was being denied."
"I should never have been charged... in the first place," he added.
South Korea's armed forces used intrusive "witch-hunt like" tactics in the search for alleged wrong-doing according to the Military Human Rights Center for Korea (MHRCK), an advocacy group in Seoul.
As part of the 2017 probe, investigators forced suspects to message dating app users in front of them to hunt down other gay soldiers, it said.
Three navy officers are currently under investigation for violating clause 92.6, MHRCK told AFP, after one revealed he was gay to a military counsellor, who then reported him.
"The fact that a military therapist disclosed the soldier's sexual orientation without consent says a lot about human rights in South Korea's military," explained the organisation's head Lim Tae-hoon.
The navy said the inquiry was being carried out according to the military criminal code, and on the orders of the defence ministry.
- 'Archaic and discriminatory' -
Authorities regularly cite the need to preserve military discipline as the main reason for the sodomy law.
"The ban needs to remain in place as it is required to maintain a sound and wholesome lifestyle and discipline in the military, which is a communal institution," a defence ministry official told AFP.
Consensual heterosexual sex is not a crime in South Korea's military, but its conscript army is predominantly male.
Allowing homosexuals to serve in the military was a highly disputed issue around the world for decades.
A landmark court ruling in India scrapped a colonial-era ban on same-sex relations last year, but the country's army chief said in January that gay sex would not be tolerated in his forces -- one of the largest in the world.
In the South, 12 of the 2017 detainees -- the officer AFP interviewed is not among them -- have challenged article 92.6 in the country's Constitutional Court.
The law has already been appealed to three times since it was enacted in 1962, and was upheld in a 5-4 ruling as recently as 2016.
The situation has been criticised by a number of global rights organisations, including Amnesty International, which called the law "archaic and discriminatory".
Last month, Human Rights Watch called for the military sodomy law to be repealed in a brief to the Constitutional Court, branding it a "blight on the country's human rights record".
Graeme Reid, the organisation's LGBT rights director, said: "Criminalizing adult consensual same-sex conduct should be relegated to the history books – it has no place in Korean society."