Jung Daehyun was part of a team of assassins named the Super Six together with five other highly-skilled boys. They were the best in their clan, and is actually the reason why their clan remained on top.

Being the silent one, Daehyun became the best ninja out of the six. He would kill other clan members who would pose as a threat to theirs and whoever they were tasked to kill, he would end the poor person's life without making any sound.

Daehyun, as top assassin, became the right-hand heir of the clan head, Master Shin. Everybody in their clan looked up to him - including the man he loved, Moon Jongup.

To Daehyun, losing Jongup would mean losing his own life. Jongup meant the whole world to Daehyun. He would take care of the younger, like a mother, but much more than that. Daehyun knew that the kid could protect himself, but he was really in love for too much that he would kill anyone who tries to kill his love.

Jongup was never oblivious to Daehyun's affection. Jongup swore that he would only be the receiving end of Daehyun's affections, but  would never fall in love with the older.

Time came that the younger had already fallen for his hyung, and a secret relationship had been forged. They would sleep together, eat together, stroll together, and most importantly, fight together.

It wasn't long that most would start to take notice of the two's affair. They never cared about it; they even confirmed it during a clan gathering. Jongup's popularity within the clan quickly rose to the top.

But the relationship between the two had angered Master Shin. He tried doing everything to separate two; including sending a female apprentice who would seduce Daehyun, hiring people who would pretend to be their respective parents, and even having their team leader Bang Yong Guk assassinate them. Master Shin was truly desperate in separating them.

The ultimate plan came when their team became tasked to eliminate a rivaling clan. This all turned out to be an ambush. Jongup had been thrown into the sea during a round-up and Daehyun was forced to watch the weakening scene of losing his lover.

The death of Jongup brought the Super Six into an endless pit of downfall. Although the clan had become stronger, the team had already separated into their own paths. They had met secretly through the years, talking about their lives in a normal light.

Bang Yong Guk had become a famous rapper and a songwriter, living with his partner Kim Himchan, who became an MC, model and an instructor for traditional music. They had adopted their team's maknae Choi Junhong and takes care of him as their son.

Jung Daehyun, on the other hand, has learned to live his life normally and lived with best friend and teammate Yoo Youngjae. Youngjae, who became a History teacher at Byungwoon Arts High School shortly after their separation from the clan, helped him to get hired as a teacher for both Asian literature and Music. Daehyun became popular in the school because of his singing voice and his looks as well.