The Moonlight King

Seoul, Korea 1977. A young couple makes the toughest of decisions.

Driven by shame they send their only son far away into foreign adoption.

Their son is just six years old.

A new country. A new life he cannot possibly understand.

He is tortured and beaten.

Broken and battered.

Forced into unspeakable acts.

He builds walls that cannot be seen.

And bars that cannot be broken.

Scars that do not heal.

And wounds always open.

Can he battle his demons?

And conquer the darkness?

The fight for freedom is within…

“The Moonlight King”

The true life story of Derek DeCosta

Library Copies Available At

The Moonlight King Library Copy


The Moonlight King Library Copy

“The Moonlight King is a true account of the power of the human spirit.
What Derek went through… to come out of it as such a being of love and light astounds me and touches my soul.
His book, and he, himself, encourage me to be the best person I can be.
I was truly surprised that he had never written before, as this book is so masterfully done.
He tells his story with such color, that it is often hard to read.
Yet, at the same time, he punctuates it with his humorous observations that sometimes caused me to laugh out loud.
Please read The Moonlight King and prepare for your life to change.”
Denise M. McShane – Screenwriter

What The Media Is Saying

The Moonlight King is an incredible book! Derek’s story will rock you; it will shake you to the core. This is right up there with the top books I’ve ever read! It’s a must read and well worth your time. It’s amazing how Derek has stayed such a positive and inspiring man in spite of the many challenges in his life.This story will stick with you, long after you’ve read it.”

– Alex Stylos
WSAR Radio Host, Somerset, MA

“Derek’s struggle adds pathos and ethos to the insight, wisdom, and advice that he weaves into every page. Forgiveness and love are the keys that finally unshackle him as he realizes his own self worth and asserts his right to an important and meaningful life. His writing style is poetic but easy to read, using powerful language and descriptive imagery to describe the ugliest of experiences and feelings. If Derek’s experiences are the thorns, this book is the rose.”  

– Jean Perry

News EditorThe Wanderer

The Moonlight King is an incredible book! Derek’s story will rock you; it will shake you to the core. This is right up there with the top books I’ve ever read! It’s a must read and well worth your time. It’s amazing how Derek has stayed such a positive and inspiring man in spite of the many challenges in his life.This story will stick with you, long after you’ve read it.”

– Alex Stylos
WSAR Radio Host, Somerset, MA



Fitness Trainer Derek DeCosta Shines Light on the Power of Positivity in his debut book The Moonlight King

by Stacey Marcus

“Forgiveness is the fragrance the violet sheds on the heel that crushed it.”

– Mark Twain

Ever meet someone so positive that you need to don powerful sun glasses to shield the rays of light radiating from their heart? Derek DeCosta is that guy, which is stunning given the past he details in his self-published book, The Moonlight King. The fitness trainer grew up in Korea in an idyllic nirvana until he was six years and his parents sent he and his older sister to America hoping to shelter them from the shame of their divorce. Instead of discovering a dream, the young boy found himself living a nightmare at the home of the family who adopted him and routinely subjected him to physical, mental, and sexual abuse until he esacped when he was 14.

He notes that the memories of his childhood in Korea and his connection to the moon (the inspiration for his book tile) helped him navigate tough times along with a belief that he was destined for something greater. When his best friend fell off a building and was paralyzed, it led him to reflect deeper into his mission in life.

It wasn’t until one of his students asked to him to write a blurb for his workout manual and video so she could sell it in Korea that DeCosta was ready to reunite with Yoon Sang Kyun (his birth name) and crystalize his mission in life which he says is to “unshackle prisoners of limited beliefs.”

The blurb transformed in a book after three-weeks of non-stop writing and crying. DeCosta, a voracious reader and light seeker, also credits his training in the military to helping him reprogram his way of thinking. “You become what you surround yourself with,” says DeCosta who looks for beacons of light in books, podcasts, mentors, and members of his ever-growing team of positive people he adds to his life everyday. “The purpose of life is not to get to the top of the ladder, but to enjoy the journey,” says DeCosta.

The fitness trainer believes in triad of wellness that includes spirit, mind, and body. He gave us four tips to navigate the holidays and beyond in optimum mental and physical health.

Drink more clean water.

Drink a gallon or more a day. Your body is made of up to 85% water in all 50 trillion cells. Hydration is the key to health and fitness.

Eat natural raw veggies and fruit for phytonutrients.

They have the ingredients that you’re made from water, vitamins, minerals, enzymes and Chi energy.

Get regular sunshine, fresh air and exercise.

Sunshine upgrades your DNA, Fresh air provides energy and healing

And exercise provides positive emotions to reward your positive motions

Most important, remember to laugh and love.

This literally creates the electromagnetic frequency to heal your body and mind

by engulfing each cell within a field of love vibration balancing our chakras or spiritual core, which vastly improves your physical and intellectual health. Remember, your heart tells your mind how to run your body. So speak kindly to yourself and others, for your beliefs create your body.

DeCosta believes that while you can’t pick your family that is part of your DNA, you can find teammates that add light to your life. He is constantly recruiting sisters and brothers to add another spoke to his wheel of hope. I was happy to be on the ride for our interview.

 DeCosta’s book The Moonlight King is available on Amazon. Visit for more information on his book and to learn more about his wellness company. 

Derek DeCosta: Finding freedom in forgiveness

By Morgan Beard Oct 13, 2021

 Derek DeCosta (right) and his older sister show rare smiles as children. The two grew apart later in life because they dealt differently with their shared trauma. She requested her likeness not be used in the book. Photos courtesy: Derek DeCosta 

MARION — When Derek DeCosta first arrived in Hyannis, he was scared and alone. He did not speak English. He did not know where he was or why his parents had abandoned him. He didn’t even know yet that his name had been changed from Yoon Sang Kyun.

DeCosta recounts in his newly published book, “The Moonlight King,” that he was just six years old when his parents put him up for adoption in Korea. They preferred to send him to America along with his older sister, rather than facing the shame of their divorce. But that was only the beginning of the challenges he would face.

DeCosta and his sister were not taken in by a happy family that would give them a better life, as their parents undoubtedly hoped. In reality, their new family was made up of one monstrous woman, her violent and abusive son, and a herd of cats that held a higher social status within the house than him or his sister.

For the eight years he lived in that house in Hyannis, he was regularly abused physically, mentally and sexually, until one day he escaped.

Most people who know DeCosta, as he lives now in Marion, probably would never have guessed that his life began with such unrelenting torment. When you look at him today, you will see only a confident man with good posture, a warm smile and a knack for conversation.

That is because DeCosta doesn’t carry those injustices with him anymore — he decided to let them go a long time ago, along with his dreams of revenge. He has learned to accept what happened to him and has realized that without it, he wouldn’t be who he is today. But he has not forgotten about it either.

Eight years ago, DeCosta, now a fitness trainer, was asked to write a blurb for a workout video he filmed that was going to be redistributed in Korea. However, the marketers thought that Koreans might be confused by his distinctly un-Korean name and wanted him to give a short explanation of how he came to be known as Derek DeCosta.

The short blurb, however, turned into an eight-hour marathon writing session as DeCosta began to put his memories down in print for the first time. After two weeks, he had written almost an entire book, though the editing process took considerably longer.

He finally self published the book earlier this year under the title, “The Moonlight King.” The name references both his affinity with the moon — which always made him feel protected and closer to his mother as a child — and his innate feeling that he was meant for something greater, which sustained him during low points in his life. 

“As I wrote this book, what I realized was that the freedom I was searching for wasn’t a physical one like I thought it was when I was younger,” he said. “Physically I left the house, physically I got my body stronger as I trained to defend myself, but the real attack wasn’t physical anymore. It was all emotional.”

DeCosta said it was not until he realized how much baggage he was still carrying that he could finally put it down. Once he did, he wanted to help others do the same.

“One of my objectives with this book is for people to read it and say, ‘you know what, I need to let go of these demons that are not serving me anymore, I need to forgive the people who hurt me and I need to live a life that is filled with passion and love,’” he said. “I really believe the point of life is to give and receive love, but you can’t do that when your heart is filled with fear, anger, frustration or resentment. So you have to let those things go to create the space for love to exist.”

DeCosta is a teacher now. And as any good teacher does, he uses the lessons of his life to help his students better understand their own.

His fitness and self-defense classes are held at his private studio in Marion. The sessions involve a mix of stretching, cardio, strength training, meditation and wellness coaching that he tailors to fit each student’s goals. Through his work, he says he strives to help his students develop themselves not only physically but mentally, emotionally and spiritually.

“I model myself after the samurai code of ‘constant improvement,’ which is a word that I use in my book, ‘kaizen,’” he said. “Kaizen is a Japanese word that means 1% improvement in every facet of your life, every single day. And the idea is that if you improve yourself in every way by 1%, even when no one’s looking, you are by default 365% better by the end of the year.”

DeCosta’s book, “The Moonlight King,” is available on Amazon in paperback or kindle format. To contact him to schedule a free consultation, call (508) 930-1861. To learn more, visit his website at or

Mattapoisett Man Shares Poignant Life Story

on June 24, 2014

It was not Derek DeCosta’s intent to write a book telling the story of his traumatic childhood when he sat down to write a foreword to a fitness book he planned to market in Korea. But when he began writing about his Korean roots, the dam that for years had held back a river of repressed memories and emotions burst, and The Moonlight King floated up from the tormented waters that flowed from the reconciliation with his painful past.

Born Yoon Sang Kyun, DeCosta lived a privileged life as the only son to his father and loving mother – until one day when he was five years old and his life changed forever. Innocence was soon lost, and the nightmare of the next eight years of his life began.

DeCosta describes in vivid, agonizing detail how his parents would divorce, and DeCosta and his older sister would be hastily sent late one night to the United States and adopted by a single mother in Hyannis, Massachusetts. The children are imprisoned and enslaved by the woman and her son, enduring years of every possible form of torture and abuse.

The book documents the harrowing process of DeCosta’s journey from the darkness of his childhood into the triumphant light of becoming a free man and a successful adult.

On the evening of June 19, DeCosta shared his message of transcendence through forgiveness and love with dozens of people during an author’s talk at the Elizabeth Taber Library in Marion.

“I didn’t write the book to write a book,” said DeCosta, calling it a form of release – a “cathartic purge” – a letting go of demons.

When DeCosta started the book, his words began to assemble shocking sentences, which developed into painful paragraphs, progressing on to bone-chilling chapters. DeCosta said he did not stop to read his own story until a few days after he finished it.

“That was difficult … to relive childhood,” said DeCosta, “in living color – with no buffer.”

Throughout his tumultuous life, DeCosta has been both a sprinter and a runner of proverbial marathons, and the readers will find themselves running alongside him, cheering him on from the sidelines as he tries to reach the ever-retreating finish line. There is relief when, finally, he does.

When DeCosta talks, people listen. There is an invisible light that emanates from his words of encouragement and inspiration as he speaks, and his message resonates on some level with the experiences of all people.

DeCosta’s struggle adds pathos and ethos to the insight, wisdom, and advice that he weaves into every page. Forgiveness and love are the keys that finally unshackle DeCosta as he realizes his own self worth and asserts his right to an important and meaningful life.

His writing style is poetic but easy to read, using powerful language and descriptive imagery to describe the ugliest of experiences and feelings. If DeCosta’s experiences are the thorns, this book is the rose.

DeCosta resides in Mattapoisett and he is a fitness trainer, life coach, and mentor. Seated inside the Taber Library that Thursday evening were some of the people whose lives have been touched by DeCosta. He has his own public access show on ORCTV called Become Your Own Gym, and he strives to assist people in discovering themselves both physically and spiritually in his own wellness program.

The book is not yet published, but DeCosta has donated several copies to the Elizabeth Taber Library and the Mattapoisett Free Library, and he plans to distribute the book to the surrounding town libraries as well. Visit for more information about DeCosta and the book.

By Jean Perry

Survival Leads to Discovery, Redemption

on December 9, 2021

He’s a grown man now, a man who has survived torture and torment, grief from immeasurable losses, disappointments and finally discovery that led to redemption of his true self. But that kind of transformation doesn’t come free of charge. It takes a great deal of acceptance and forgiveness, qualities that are found in vast quantities in this man – Derek DeCosta.

DeCosta, author and entrepreneur, is now pursuing another passion, possibly the most important one for himself and others, to share his journey so that others may make their own discoveries, find their own redemption from their living hells. DeCosta is gaining momentum as a motivational speaker.

Since 2014, when a local print shop helped DeCosta produce and distribute 100 copies of “The Moonlight King” primarily to book clubs, much has been written of the author’s passage from his comfortable home in Korea with an intact family to his parents’ divorce, which for him and his sister meant being given away to an orphanage.

Seven years later, the book has been officially printed and released by Gatekeeper Press, a publisher just outside Columbus, Ohio. In 2021, many more are reading DeCosta’s compelling story.

As he tells it, divorce in Korea was so heinous, so shameful, that all evidence including any children produced from the marriage needed to be erased. Thus DeCosta and his sister, just small children at that time, would ultimately find themselves being placed in a tragically hostile home on Cape Cod, where abuse of every conceivable type rained down on these innocent beings for years.

He would come to realize there were only two choices: Sink into total despair and failure or rise above and fly away to discover who he could be. He would eventually choose the latter.

On December 1, DeCosta spoke to a supportive audience both in person and via Zoom, one of a growing number of local authors that the Mattapoisett Library has hosted as part of its local author series.

DeCosta said that the years of abuse could have created in him a person who would take a dark path, but “ultimately I choose redemption.”

 His redemption would be a complete mind, body and soul makeover. “In spite of the trauma,” he said, “the horror of living with evil, I found I could save myself through reflection and healthy goals.” The author fully believes that taking good care of one’s body must be part of the program for a healthy lifestyle, and thus it has become a big part of how he spends his time, helping others to strengthen their bodies.

 DeCosta said he wasn’t out to make money off the sale of his book but instead wished to use it as a springboard by which he can reach as many people as possible with his story and the tools needed to free them of negative forces.

“Change how you think about yourself,” was one bit of advice DeCosta shared. “You become what you believe, what your surround yourself with.” He credits the good people he eventually found with helping to shape the belief system he now promotes for himself and others. A major takeaway was a rather simple but oftentimes overlooked reality. “Your happiness is your responsibility,” DeCosta asserted.

Throughout his hour-long presentation, DeCosta shared tattered pieces of his time living with his adoptive parents, a time when he believed his mother surely must have been looking for him. The images that those memories conjure up demonstrate the bravery, shear strength of will it takes to overcome devastation. DeCosta knows he’ll spend a lifetime recovering from what others did to him, but he refuses to define who he has become or rob himself the joy that life offers, including love.

DeCosta told of being reunited with his mother after she had come to America. The little boy in his soul imaged a warm reunion. What he found instead was a woman with her own demons, unable to be a mother and lacking the insight or desire to become one. “She was just a very immature person,” he said. DeCosta had to accept a second rejection and the reality she had not been looking for him.

Many elements from many philosophies whose core is “the power of positive thinking,” a process first introduced by Dr. Norman Vincent Peale, are part of DeCosta’s message today. He talked about the Kaizen method of continuous improvement and the wheel of happiness, a system for gauging how satisfied you are with the use of your time.

In the current release of his book, DeCosta has added some concrete guidance for those just beginning their journey of discovery and redemption. He wrote of finding and “drafting” likeminded people to help, cutting off toxic relationships, having the strength to walk alone, staying humble and taking “massive” action. The end of the book contains other positive guidance tools.

The Moonlight King is assuredly a story of survival and redemption, but it is also a story that will continue to be written throughout DeCosta’s life, for the journey of continuous improvement doesn’t have a finish line.

 To learn more about The Moonlight King and Derek DeCosta, visit

By Marilou Newell