Morning comes and Luffy eagerly started the day by bothering Luke for a spar.
"It's still early to have a spar. No offense but you are too weak for that. First, you need to improve your physique for better control of your Devil Fruit ability." Luke crossed his arms.
"But I think I'm doing good. I can even crush a giant boulder with ease." Luffy disagreed. He has his own insight with things and thought that having continuous battle will greatly improve ones' capability.
"Oh? Hehe. Alright, I'll listen to you then. How should we spar?" Luke raised his brows with interest.
"Of course we fight." Luffy excitedly smashed both of his fist.
"I hate to break it to you but you will probably go down on our first clash. Haha." Luke laughed out with confidence. He continued, "Do you remember? You assigned me to be the training mentor of all the future crewmates including the captain and you already forgotten it."
"Nshishishi Yes but I also said you need to handle those stubborn mates including me." Luffy laughed.
"Hah! Fine. I'll let you know how weak you are. I heard people in the Grandline are powerful monsters. I may considered as one. Let's see how close you are to them then." Luke beckoned Luffy with his finger, indicating the latter to start the fight.
"Yosh! Here I go!" Luffy excitedly assumed a horse stance. He shouted, "Gomu-Gomu No! Pistol!"
Swish!
Luffy stretched his fist backwards, then he whipped it forward really fast.
"Haha. So this is how your ability works? But I don't think your fist is as fast as a pistol." Luke chuckled as he waited Luffy's punch with patience.
"W-What happened?" Luffy who already threw his punch midway, gasped in shock. That's because, his punch is as slow as snail. He can talk, but his body was like slowed down by couple of times. He even have a hard time moving his body.
"If I were your enemy in the Grandline with similar ability, what will you do in this situation? Should you wait to be killed helplessly?" Luke searched for some tools and only found a wooden club. He smirked and grabbed the club while approaching the nervous Luffy.
"W-What are you doing? This is cheating! Fight me fair and square!" Luffy shouted but his plea went on deaf ears.
"Haha. All is fair in love and war. In some situation, you need to be unfair just to get what you need. This is my first lesson to you, captain." Luke's harmless smile made goosebumps all over Luffy. He continued, "Grandline has another name to it. It is called Pirate's Graveyard. Countless pirates perished in that place in search for One Piece.."
Luffy watched Luke helplessly as his body refused to move no matter what he do.
"Bang! You died." Luke assumed his wooden club as pistol and aimed at Luffy's head up close.
"I can't die. Bullet's don't affect my body." Luffy snorted while struggling to move.
"Good point. However, there's a special bullet made by the marines to deal with pirates who used Devil Fruits. These bullets can penetrate your head like it's no big of a deal. It is made by a special material called Seastone." Luke smiled. He continued, "Seastone. This thing is like a normal stone but harder than steel that resides at the bottom of the deepest sea. This thing is the enigma of all Devil Fruit users. Not even the mightiest can escape it's lethality."
(A/N : Actually making things up regarding Seastone. Creating Seastone is a complicated process. Just follow my fanfic description.)
"How is that possible? No way right?" Luffy asked in disbelief.
"Yeah. So think again before you died laughing from a random Seastone bullet passed your head." Luke squinted his eyes while knocking on Luffy's head lightly.
Luffy remained silent. He can now move as his body returned to normal. However, he was bowing down like in deep thought.
Luke crossed his arms while he leaned on a tree. This is his way to remind Luffy that facing a random battle may cost him his life in an unpredictable way. He still wanted Luffy to face a setback in order to grow up though.
"You're right, Rooku. I may be ahead of myself. Thank you for the reminder." Luffy lifted his head and faced Luke in a serious manner. He was thankful that Luke can provide him some sense at least in terms of safety.
"Don't worry. People who used Seastones are very scarce in numbers. Most of them are in Grandline too. Plus, Seastone is a heavy and rare thing for pirates. You will have a small chance on detecting it out of the raining bullets, this thing have a distinct air travel. If you noticed it, you might have a little chance of survival." Luke stated.
"So how should I enhance my detection senses then?" Luffy asked in anticipation.
"We'll come to that soon. For now, you need to improve your physique. Perhaps you might escape my control with sheer physical strength."
"Really?" Luffy's eyes shined.
"But I'll double the pressure when that happens. Hahaha!" Luke laughed out loud.
"Ugh.. I should call you cheater." Luffy grumbled. However, he already saw a light on how to defeat Luke. He only needed to surpass his limits.
"Stop whining. I will use my ability on you now. This will increase the gravity of your body." Luke touched Luffy's head. His crimson eyes shone in red light.
"Woah! Amazing! I can actually feel my weight getting heavier a couple of times!" Luffy jumped upwards. He asked in confusion after he noticed something, "I feel strange. Why am I still light after landing? Shouldn't my landing have some weight too?"
"Don't worry. That's how my power works. I can let you gain weight while staying light. You'll still struggle just like usual, you will feel heaviness of your body, the slowness of having a heavy body and gaining benefits for having such a body. You'll get used to it in no time." Luke explained slowly for Luffy to understand.
"Okay! That sounds amazing indeed!"
"Right now, your body weight is fifty times heavier. Also, I put a limit on your body to a thousand fold. If you want to increase your weight, press your left temple. To decrease, press right. Easy." Luke smiled while his face was getting paler, but he appeared nonchalant.
"Yahahaha! With this, I will be able to improve by leaps and bounds." Luffy played with his temples again and again to test everything is real. His eyes sparkled like shining stars with the discovery.
"Hehe! Rules is this. You can't lower your weight even when sleeping. The same with finding food in the wild. Unless you face eminent danger, don't lower your weight at all cost. You will know when the time comes after we undo my power on you." Luke smiled. He wanted Luffy to transform into something new after the undone. He continued, "I know you received some inspiration after I enhanced your body yesterday. Work that out while you're in this state. With it, you'll gain double in rewards."
"Ooouh!! Realy amazing! You also noticed that?!" Luffy was surprised. Someday, he may turn numb on how Luke can surprise him, but not today. Luke never ceased to amaze him when it comes on his vast knowledge. Every time Luke reveals something, his worldview changed greatly at a time.
"Thank you very much. It's my pleasure, captain." Luke bowed with elegance as he smiled.
...
Luke laid on a tree branch while Luffy does his training on the ground walking and tumbling like a baby trying to balance his body after learning how to stand.
Luffy actually increased the gravity of his body a hundred fold. A bold action but expecting no less from Luffy, a stubborn kid.
Meanwhile, Luke closed his eyes as if he was napping. While the truth is that he was recalling his fight with Garp last night. He was observing the properties of the Armament Haki.
Last night, he could vaguely see the darkened fist of Garp since he doesn't fully know how to use Observation Haki.
Only those who mastered Observation Haki can see the other Haki clearly. In his previous world, Luke hardly recalled the requirements on how to practice Armament Haki.
To start, there are three kinds of Haki, Observation, Armament and Conquerors.
From his own understanding, Armament Haki is the easiest one to practice given how sturdy his body. Even though his inherited power allows him to apply what he saw at first encounter, but when it comes to Haki, it's a challenge.
Just like Rokushiki Techniques. He can easily learn those skills at one glance.
However, the concept of Haki is a bit complicated. He can easily apply a Haki in his hand in an instant which gives his hand the feeling of hardness. However, he can't see the progress without Observation Haki.
He will have to get beaten down first before mastering the Observation Haki. Training it is hard too. One needs to clear the mind while evading the incoming attacks from every direction.
As for Conquerors Haki, Luke left that to fate. He's not interested in that concept for the time being. He has a similar suppression ability himself but with different effect and he wasn't planning on replacing it so soon.
As for someone trying to bend his will, Luke smirked without giving any comment.
"Hmm?"
Luke squinted his to the side and saw Killer Bee crouching on another tree branch.
"Sometimes, I kept wondering if you really are... you after that accident. You are a totally different man after gaining power." Killer Bee made a side comment.
"In a good way right?" Luke replied with a smile.
"You think so?" Killer Bee clicked his tongue in annoyance.
"You are early. Any news?"
"...Yes. Our boss wants to talk to you." Killer Bee nodded.
"Oh yeah. You didn't told the name of your boss. May I know the esteemed name?" Luke raised one of his brow with interest.
"No. But I can only tell you his alias." Killer Bee shook his head as he continued,
"His alias is..."
"Pain."