For the past few months, Sakura had been trying to create a brand-new elemental Kekkei Genkai in her spare time, but with no reference point to build on, her patience had quickly worn thin. Tired of obtaining no discernible results from her experiments, she'd decided after a while to set that project aside and focus instead on the S-rank Ninjutsu she'd earned for thwarting the overseas invaders' attempt to conquer the shinobi continent.
If nothing else, she figured, it would at least make her less helpless against gigantic enemies like the Tailed Beasts.
"Ugh, mou~! This is impossible!" shouted Sakura, stamping her foot in frustration. "How exactly am I even supposed to use this! Who designed this stupid Ninjutsu, anyway!? I'm going to give them a piece of my mind…!"
Sakura stalked across the training grounds and snatched the Jutsu scroll from the tree stump where she'd left it. She then unfurled it in one go, scanning the scrawled instructions and esoteric diagrams until her eyes landed on the three words at the very bottom: Created by Orochimaru.
"#$%#@#!" snarled Sakura, hurling the scroll to the ground with the force of a thousand exploding suns. "Who else!?"
The Electromagnetic Induction Weapon Launcher Jutsu— better known as the Lorentz Gun Jutsu— was the S-rank Lightning Style Ninjutsu that Sakura was currently trying to learn. This technique didn't rely on the Kazekage's fake Magnet Style, which was a combination of Earth and Wind Styles, of all natures— it used real electromagnetism with real electricity!
'This is a lot more difficult than we initially thought,' said Inner Sakura glumly. 'If only Sasuke had enough chakra to use this Jutsu, we could use our new Sharingan to copy him and cheat out the comprehension part…'
Despite her increased affinity for Lightning chakra, Sakura was having trouble getting through the introductory phase of the Jutsu. Everything about the technique felt like it belonged in hell difficulty mode— the hand signs, of which there were a whopping fifty-two to remember, and the massive chakra cost of around 1.5KK per shot… among other things.
Firstly, creating the electrical current (and maintaining it in midair, no less) that would generate the magnetic field was hard. By now, Sakura could easily create simple electric fields between her hands without relying on hand signs by imitating a capacitor, but this was on a whole different level of impossible, for reasons that will be explained a bit further.
Secondly, the Lorentz Gun Jutsu required an enormous amount of chakra. Even for Sakura, it took a lot out of her to generate the current needed to construct a magnetic field powerful enough to launch metal projectiles at supersonic speeds. Each time she fired the technique (or misfired, more often than not), it would consume more than an entire Kakashi's worth of chakra, severely limiting how many times she could practise it in a single day.
However, the most difficult part wasn't even creating the current and the magnetic field, it was aiming and timing her shot. For an attempt to count as a success, Sakura would need to throw her metallic projectile perfectly perpendicularly through the current the instant it reached maximum power— which was easier said than done— and then not miss her target.
'In other words, good luck trying to hit a moving target …' said Inner Sakura grimly, 'This Jutsu is only good for sniping unaware targets, or hitting targets so big I couldn't possibly miss if I tried...'
On Earth, railguns had been popularised by A Certain Show About Cute Girls Doing Cute Things, but railguns weren't the only type of electromagnetic gun— they typically fell into one of three broad categories: railguns, coilguns, and Gauss guns.
Without a doubt, the Lorentz Gun Jutsu belonged to the first category.
FEEL FREE TO IGNORE THIS PART IF YOU HATE BOOBS (and also science)
Charges at rest create electric fields, and moving charges create both electric and magnetic fields— but to avoid overcomplicating things, let's just focus on the magnetic field component.
Just like Misaka Mikoto, Sakura can't rely on actual metallic rails to launch her projectiles, which means that she is forced to manifest her current— her moving electrical charges— in midair, by using her chakra as the medium.
First!
The direction of a magnetic field is determined by the right-hand rule (thumb pointing in the current's direction, the other four curled fingers representing the magnetic field lines' direction).
If the current loops from Sakura's right hand to her left hand in an arc shaped like a ∩ in front of her, then the resulting magnetic field lines— through which her kunai will travel— will always point upwards. Easy enough, right?
Second!
Without a kunai in between to launch from her railgun's rails, Sakura would simply have something like this: ||. However, by adding in the kunai to close the circuit, she would get the ∩ shape from before. When the kunai travels along the rails, making a longer and loooonger ∩ as it goes, it allows the current to flow from the right rail to the left rail.
Since it's the kunai we're concerned with, the charge's velocity vector is right to left.
Third!
Charges moving through a magnetic field follow the right-hand rule. The velocity of a charge, the magnetic field it travels through, and the resulting magnetic force are all at right angles from each other.
You can try it yourself with your own right hand in front of you, distinguished reader— index finger (velocity vector) pointing left, middle finger (magnetic field line) pointing upwards, which leaves your thumb (Lorentz force) pointing away from you— and in the direction of your enemies, hopefully.
Because that Lorentz force is what's going to launch your butter knife at Mach 7 speeds!
Ok, You Can Come Back Now
"Orochimaru obviously didn't finish this Jutsu," grumbled Sakura. "This sucks, I totally got scammed…"
Sakura was correct— in his quest to learn and master all the techniques the world had to offer, Orochimaru had created a bunch of impressive but impractical S-rank Ninjutsu, for the express purpose of contributing them to the village to redeem merits for the Scroll of Secrets' Jutsu.
However, even though the Lorentz Gun Jutsu was clearly unfinished, that didn't mean the concept in itself was bad. The Jutsu just needed some fine-tuning— maybe a hand sign could be cut here and there… and maybe the output could be lowered a bit, too. Sakura also needed to find a way to stabilise the current— all things being equal, there were also Lorentz forces acting on the 'rails' themselves, which kept causing her Jutsu to fall apart before it could launch anything.
"I just need to steal one elemental Kekkei Genkai," Sakura thought to herself out loud. "If I had one, I know I could develop the ultimate Jutsu by combining Kekkei Tōta with the Lorentz Gun Jutsu…"
The Wind and Fire natures combined gave birth to the Scorch Style Kekkei Genkai. Wind, Earth and Fire together made up the Dust Style Kekkei Tōta. But what would happen if Sakura combined her three primary natures? Fire, Wind, Lightning… she couldn't wait to find out!
'That's putting the cart before the horse,' said Inner Sakura, shaking her head. 'At least try to get Scorch Style or the Lorentz Gun right before shooting for the stars…'
…
Feeling a little embarrassed by her earlier outburst, Sakura cast a quick glance around to make sure no one was watching, before picking up the dusty Jutsu scroll lying on the ground.
"Karin, are you there…?" Sakura called out tentatively.
Satisfied she was alone, Sakura slumped onto her tree stump and started reading the instructions all over again. If she still couldn't get it right then, she'd give in and enter Breast Meditation to ask Orochimaru's chakra imprint for pointers…