Flashing Dash and Flashing Scabbard

Gregory avoided Fein's attack by pivoting his right foot; the attack would have hit him if he hadn't been so quick. Gregory repositioned himself while also gathering his entire weight in his left arm in preparation for his next attack. Gregory slashed the shadow in his peripheral vision with all the force he could muster in his arms. As he slashed through it...

*SHHHHH* The air produced a creaking sound.

Fein was standing behind Gregory... He had a wide smile on his face and his eyes were scanning Gregory's face and body as if calculating something. Gregory stomped his right foot on the ground to increase the speed and power of his attack. Without Degu, this is Gregory's current strongest blow. The arm he was using moved a few centimeters as his attack was about to hit it, and his attack just grazed it, producing a flickering sound. His attack landed on the ground... It makes a wheezing sound, and a crack emerged, spreading at least three meters around where his attack landed.

When Gregory looked at him, Fein's expression had turned cold and calculating, and he had a victory smile on his face. As Fein accelerated in his direction as if gravity and friction didn't exist... It was an odd, unfamiliar movement... His body had the appearance of a phantom... Fein was walking towards Gregory, his movements fluid. Gregory decided to punch him with the other arm he had available. Fein just continued after seeing Gregory's move and became even faster than before, charging in a straight line toward his fist.

"Are you insane? You'll die if my attack hits you," Gregory exclaimed in panic.

Gregory attempted to retract his fist, which was only one meter from the face of Fein, but due to excessive force, it proved difficult, when suddenly... Fein's body came to a halt instantly, Gregory's attack was only a few centimeters from his cheeks, and this was not the end, as Fein's body stopped abruptly instantly and accelerated at a faster rate than before. The terrifying thing is that, despite the speed, there was no sound to be heard... It was deafeningly quiet as if he didn't exist at all. Gregory only realized a presence on his back when he felt the sensation of a cold and sharp, metallic object on his neck.

Gregory turned around and stared at him blankly; Fein had his usual smile on his face as if he had just done something insignificant...

"How did you do that?" Gregory asked while trying to calm himself.

Fein gave him a serious look. "It was a family technique passed down by my predecessors called "Flashing Dash." the ability to essentially "teleport," or move so quickly that one loses sight of the user in an instant. In the past, I couldn't use it because, without a tough body, it will severely injure you when using it. Because the principle of this technique is to let the body reduce its resistance to friction at the lowest possible point.

Gregory looked at Fein in horror, realizing that if that was true, Fein had the potential to become the most powerful assassin... Consider someone who can accelerate whenever he wants without making a single sound. He can literally kill anyone silently if you prepare and condition him properly.

"If that's the case... if you don't die young, your future is limitless," Gregory clenched his fist in excitement.

Gregory was happy and proud that two of his students were talented; technically, He is considered his half-teacher because he taught him everything he knew.

"I will request a special dagger for you at Headquarters... Having a future powerhouse like you is beneficial to our organization," Gregory stated confidently.

Fein came to a standstill for a brief moment, as if pondering something. "You're the best Captain... I will not let you down." He looked at me and saluted with his hand on his chest, his face solemn...

"Forget it! There was no need for such a thing. After all, we are all comrades-in-arms... I am confident that someone trustworthy like you will be watching my back in the life-or-death situations that will arise in the future," Gregory said with a smile.

...

Fein was finally home, and they sparred with various weapons to see if his talent worked on all the cold weapons, and it did. He chose not to reveal his trump card, "Flashing Scabbard." He intends to use it only as a last resort. This technique enables him to attack extremely quickly with sharp, small weapons such as daggers and knives. Fein actually tried a thousand times to imitate the techniques in anime by deducing the principles and perfectly replicating the motions using his B-ranked memory and martial arts talent.

As you can see, He succeeded in innovating the Nanaya family's arts. Fein actually started working on it a year ago with no success. He finally met the conditions to do it only recently, thanks to his talent reaching B-rank and his body becoming stronger. Even if he decides to teach it to someone in the future, he must be as talented in martial arts as him. Otherwise, it will be pointless. Fein's ability to improve his skills in all areas was extremely valuable.

One must understand that even the most brilliant or multi-talented person in the world will have weaknesses in some areas. That, however, only applies to them, not to Fein. In his previous life, there was a proverb that said, "A jack of all trades is a master of none, but oftentimes better than a master of one." In that case, He will simply become the master of all!

With Fein's discovery, it appears that his "PLAN H" to become stronger requires some additional polishing... Following that, He intended to create his very own assassination techniques and training regimen that is suitable for him. However, He had to exercise caution when electrocuting and poisoning himself. It will be a very painful process just to increase his resistance to electricity and poison to a top level. But Fein will do it in order to grow stronger. "NO PAIN, NO GAIN" is an old adage, but it's also very true. If he wants to be among the best, He needed to become more determined than even Eren Yeager. because logically speaking, the only way to achieve your dreams is to step upon the dreams of others.