Back then, I was a demon.

Once, there was a famous adventurer in the Royal Capital's guild. Fearless and hot-blooded. He never backed down from a fight and was the first to charge when a strong enemy appeared. He braved dangerous requests without hesitation, climbing to the rank of Silver with nothing but his own skill. He earned a nickname.

"The Furious Jackknife"

To those who knew him then, no name could have fit better. His skill was undeniable, but he was incredibly quick to pick a fight. Fearless, he didn't care for a bit of danger. He was truly a man on the rise. That man was you. And eventually, even you fell in love with a woman. Her name was Foe. A Wind-attribute back-line mage who had run away from a noble house to become an adventurer. She was a comrade who had shared many missions in the same party. Serious, polite, and a woman who valued coordination with her allies. She was a natural nurturer, a stark contrast to your hot-blooded nature. As you shared the hardships and joys of adventuring, you became lovers and dated for years. Eventually, you promised to marry each other. You overcame countless dangers, made a name for yourself, and were blessed with a lover you adored. Everything was going perfectly. At least, back then. However, those days changed drastically due to a single, massive injury. During a mission, you suffered severe damage to your Mana Core, the organ that handles mana. Though your life was saved, your ability to generate, manipulate, and output mana was crippled. The elemental magic you once wielded freely now had the power of a mere teardrop. Even when you could discharge mana directly, the output was negligible. Furthermore, the injury caused your physical functions to drop to less than half of your prime. Your total combat ability was not even ten percent of what it once was. For a man who had lived as a Silver-rank adventurer, it was a devastating change. It was no longer possible to run across the battlefield as you once did. And so, the "Furious Jackknife" semi-retired from adventuring. But life itself hadn't ended. Fortunately, you had enough savings from your active days. Even without your combat strength, the experience and knowledge you gained as an adventurer remained. You began a different life, mentoring and looking after newcomers at the guild. And above all... you had Foe.

Foe stayed by your side even after your injury. Even when you lost your strength and semi-retired, her love didn't change. Foe, always the nurturer, looked after you even more, and the two of you continued your peaceful life with the promise of marriage still intact. And in that house, there was one more person. Your foster sister, Emma. A reliable girl who was good at cooking, laundry, and cleaning. She took the lead in housework and looked after your daily life. However, her way of nurturing was a bit different from Foe's. She usually had a sharp tongue and a skeptical look, nagging her brother without restraint. Yet, she would fall into a total panic if caught off guard—a rather amusing sister. Foe and Emma. Surrounded by them, you spent your days mentoring at the guild. You could no longer go on adventures like before, but you had no trouble living, and you had time to spend with the people you loved. The once hot-blooded adventurer had found a peaceful daily life. However, that peace was suddenly shattered one day.

A lover of many years. A woman who had supported you devotedly even after your injury. Foe, who lived with you and was promised to marry you, suddenly told you it was over. Furthermore, she said she was going to the side of Count Tyler. Tyler was a nobleman Foe had known previously, a powerful man with high status, wealth, and even a private army. On the other hand, you were now just a semi-retired former adventurer. Even if you were once famous as a Silver-rank, your Mana Core was damaged, and you couldn't fight like you used to. And here was the woman who had been your lover for years. Foe, who had adventured with you, supported your life, and promised to marry you, was suddenly ending the relationship. What on earth happened? Without knowing why she made such a decision, the relationship came to an end. To those around you, it was accepted that Foe had chosen Tyler of her own accord and broken things off with you. Thus, the "Furious Jackknife" lost the lover he had been with for years. But the tragedy didn't end there. In fact, this was only the beginning. Returning home in despair, you found that your foster sister Emma was gone. Emma, who always did the housework and nagged you. No matter where you looked in the house, she wasn't there. Time passed and she didn't return; she wasn't back the next day either. You began to search for her. Following the sudden breakup with your lover, your sister had vanished. After a long search, you finally obtained information about Emma's whereabouts. That place was a mansion owned by a slave trader on the outskirts of the capital.

What awaited you there was an unbelievable sight. Emma was in a cage. The foster sister who always did the chores, looked after you, and nagged you. That Emma was locked in a cage as a slave. The master of the house was the slave trader Baldo. In this country, slave trading itself was legal, and Baldo was a merchant who profited from it. Baldo claimed he had purchased Emma in a legitimate transaction. He told you to pay if you wanted your sister back. However, the amount was insane. As a former Silver-rank adventurer, you had substantial savings. Funds enough to live without trouble even after semi-retirement. Yet, the ransom Baldo demanded was something you couldn't possibly pay, even with all your savings. In the first place, why was Emma in the hands of a slave trader? Baldo only repeated that he bought her legally, and you had no evidence to overturn his claim, nor any way to prove it was a kidnapping. Your sister was definitely there, across the bars. And yet, you couldn't take her home. Then, things got even worse. You were beaten by Baldo's thugs and thrown out of the mansion. The Silver-rank adventurer who was once matchless. The fearless "Furious Jackknife." That person was now no match even for a slave trader's henchmen. Against opponents you could have handled effortlessly in the past, you couldn't even resist. And so, you left the slave trader's mansion without your sister. Your long-time lover was gone, and your precious sister was in a slave trader's cage. The combat ability you once took pride in was lost, and the savings you thought were sufficient weren't enough to get back even one sister. Back then, I was a demon. But now, your former glory was useless against the reality before you. Then, the story began to roll in a strange direction. Dragging your battered body, you walked through the capital. Where had you walked? Before you knew it, you had entered a back alley you didn't recognize. A place with a dim, somewhat eerie atmosphere, a far cry from the bustling main streets. It was a black market, a place you would normally never set foot in.

And in one corner of it...

There was a strange stall. You couldn't tell at a glance what it was selling. Combined with the dim atmosphere, it didn't look like a shop doing normal business at all. Or rather, the figure inside the stall was strange... As if guided, you visited the stall.

Long, beautiful silver hair. Transparent blue eyes. Wearing high-quality "strange clothing," she was a beauty that took your breath away. Standing in the stall, she looked out of place in the dim back alley. For some reason, the woman showed interest in your battered self. Not only that, she even treated your wounds. Then the merchant asked about the events you had experienced. How you were once famous as a Silver-rank adventurer. How you damaged your Mana Core in a major injury and lost your strength. How you lived with your lover Foe and foster sister Emma after semi-retiring. How Foe suddenly broke up with you, and then Emma went missing. How you finally found Emma locked in a slave trader's cage, and an exorbitant ransom was demanded. And how you couldn't get Emma back and were beaten by the slave trader's thugs. After hearing your story, the merchant...

"Oh, my, my...!"

Suddenly, she began to laugh joyfully.

"A once fearless adventurer. To lose his power, be left by his lover, and even have his precious sister stolen...!"

The merchant stared at you, giggling.

"Fufu! Isn't this a truly delightful comedy?"

Apparently, to this woman, the misfortune of others was excellent entertainment. In fact, she had become quite cheerful.

"My, my, thank you for such a wonderful story. I love watching mortals struggle to live. You short-lived ones are truly an endless source of interest."

After she finished laughing, the merchant reached into the back of the stall as if she had an idea.

"I know... Yes, since you told me such a delightful story, I'll give you a little souvenir."

With that, the merchant pulled out several strange items. All of them were mysterious things you wouldn't see in a normal stall. Where on earth did she get them? What were they even for? Did these things even "exist in this world"? The merchant lined them up in front of you and smiled brightly.

"Now, don't be shy. I'll give you one of your choice. I'm sure it will add some color to your life from here on, fufu..."

The adventurer once called the "Furious Jackknife." His life was about to enter a new phase through his encounter with a single, strange merchant.