Infinite Plain - Water 
His sword was the most important thing in the simple equation that was his battle prowess. The more he killed, the more power it would gain, so he was determined on mastering the sword with the technique he had newly discovered.
One of the major goals he wanted to achieve with this technique was an instant activation and a higher starting point. If his base momentum was higher, he could get to his previous level faster.
Ken picked up his now cherry red jian and thought, Flow.
Droplets of water appeared on the blades edge, and when he swung it, more water appeared, seemingly creating an endless flow behind it. A few seconds later, the harmless puddles worth of water dropped to the ground.
He immediately felt a spasm in his leg and lost concentration. The water droplets that had formed on his jian flowed to the ground. His body was still repairing itself, but he found it hard to wait. This new power he had gained was exciting for a youth like him. His innocence was still not gone, so he had always imagined what it would be like for him to gain superpowers.
Now, to dance. Flow. The concept behind that technique was the constant accumulation of momentum, so he couldn make singular slashes. The sword art he wanted to create replicated the properties of water, so had to perform a single, continuous slash that would take different forms as it flowed.
Even as his body screamed for him to rest, he forced it to move. He swung his sword with graceful and wide arcs from below and above as he slowly gained momentum.
He would duck and shift his weight according to his desires. His wave lengthened and became wilder, but still maintained its deadly sharpness.
White mist would often come from the waves crashing on each other as Ken made smaller and more exquisite moves.
His wave rushed behind him, and the lapping and splashing noises it made calmed Ken even further. It sounded like how waves would crash against the beach. Calming and soothing.
Five minutes later, he was still dancing across the grassy fields. A long, gushing tide followed his jian, which created whizzing sounds whenever he swung it.
Pleased with his rapid progress, Ken slowed to a stop, and the river behind him folded back on itself before crashing to the ground.
He tumbled to the ground, cutting himself a few more times in the process. Some of his clotting injuries even reopened as he rolled across the grassy plain. Blood began leaking from his gashes, which made him dizzy again. Ken had suffered a lot of blood loss during the battle, and his body hadn recovered from that either.
Time to sleep, he thought, calming his thoughts again and summoning a ball of water and placing it in his mouth. The water was cool as it sloshed inside his mouth. It was refreshing, to say the least. His last thought was, Cool, before he fell asleep again due to overexertion.
When Ken woke up for the second time, he took a deep breath and regained his composed demeanor quickly. He needed the ability to summon his waters whenever necessary, so he had to keep himself impassive at all times.
Ken was feeling much better now that his body had healed. His muscles were still a bit painful to stretch, but it was bearable. Unlike the burning pain he felt back then, it was now a bunch of needles poking tissues.
He raised his hand, and an orb of water was fabricated in his palm.
Nice. He summoned a huge glob of water right above him. Controlling it wasn his intention in the first place, since he knew it would be impossible at his current level. He wanted to use it to wash himself, and dumping a pools worth of water on himself was the best way he found to do that in a short amount of time.
A giant wave of water picked Ken up and washed him a few meters away. He came out of the wave soaked, but laughed to himself, ”I never new baths could be this fun! I should do this more! ”
Then, an idea hit him, Speaking of riding waves… he put his hands to his chin, Can I ride a surfboard made of water?
Ken jumped up and summoned a plate of water. It was a few centimeters thick, but he reached the ground before he could even think of solidifying it. So, he tried another approach. He summoned the water beside his feet and stepped one foot onto the aquatic surfboard.
He let his feet sink a few millimeters into the water before ordering the water to condense.
The surfboard became smaller as it heeded Kens commands, compressing until he could feel the water like it was some sort of mud or putty.
But, the second he put his other foot onto the surfboard, the entire thing collapsed, unable to handle his weight. He tried the technique a few more times, but it was futile. He did not have enough of a mastery over his hydrokinesis to hold such a large mass with his water yet.
Sighing, he decided to put any thoughts of creating a flight technique on hold for now. If he couldn make the water hold his weight, then there was no reason for him to continue testing, Unless its because water simply can do that. There was this thing called buoyancy. He was too heavy, so the upward force exerted by the water couldn counter the force of gravity pulling Ken downward, resulting in him sinking.
If he applied the same theory to his technique, then he would either need a solid platform to stand on, or he would have to fly by floating in a portable mini-ocean.
Even if that were the case, he couldn know, since he didn have the means to test it out.
Whatever, I should probably just focus on my swordsmanship for now. He flicked his sword and began swinging.
This time, he went for a more traditional type of training. Swinging forward. All he did for the next hours was practise his accuracy.
There was no target to slash at, so he didn know how good his improvements were, but he still tried to keep track of his progress. Every few hours, he would switch from one slash to the other, practising the most basic movement horizontally, vertically and diagonally until his arms felt ready to fall off.
By that time, a day had passed, but he was able to go on. Since his bodys healing, his stamina had increased by a decent margin, but Ken still noted that it was by an abnormal amount.
Normally, it would take a week to slightly enlarge ones stamina pool, but it had taken him only one serious burn out, and he had expanded the boundaries of his limits by a good chunk.
Nonetheless, he sat down on the ground and took a break to let his body disperse its accumulated stress. It wasn good to overexert himself too often.
Once he felt properly rested, he began his workout again. He would slash and hack in every direction, and he even did some stretching to allow more flexibility into his fighting style. It would be embarrassing if he died because he got a muscle cramp from stretching a bit too far to the left.
After his training, he felt like it was time to go hunting again. Ken was not eating the corpses of those nasty sewer rats, especially when they were raw.
Ken began sprinting across the field, running at speeds he had never before run at. He was faster than an average car by now, and that wasn the full extent of his speed.
If I keep tiring my body out like this and letting it heal, I might reach superhuman levels of speed, Ken thought, picturing himself going faster than an airplane.
A small figure appeared in the distance, but Ken wasn sure what it was, but when he got closer, the monsters outline became apparent. It was another, damned rat. Which, naturally, made Ken groan.
Not only did it reach his waist in height, its stench was even more revolting than its smaller counterpart.
Ken flicked his jian, and droplets flowed from its edge, turning the blade into a wave that left a trail of water behind it. As he ran, the trail of water slowly became sharper more violent.
He leaped forward, his river moving behind him like a ribbon, and slashed with most of his strength, hoping that it would be enough to cut a fatal wound in it body, and its body.
He swung his jian, and before the rat could even react, it was severed in half. A horizontal slash had made a clean cut in the monsters belly. It tried to move, but its top half slid off of its waist a few seconds later.
A triumphant smile appeared on Kens face as he realized he had decimated his enemy without even having to struggle.
He stopped, kicking up dirt and grass as he stared at the corpse leaking blodd from its severed parts. Thoughts ran through his head, forcing him to come to the reality that he had taken a life. No, hundreds of lives.
After this realization, he felt calm as could be. In fact, in a corner of his untrained mindx he felt a bit… Happy.
Battles were exciting, spilling others blood in exchange for power was thrilling. His smile turned helpless as he said, ”I am a battle maniac. Maybe even a psycopath. Well, at least I don get boners from killing things. ” He chuckled at his own joke and put the jian down to let it absorb the rats blood.
The sky turned silent seconds after the giant sewer rats death. No lightning. No thunder, until a giant bolt of lightning rained down upon the plain.
So it happens every time I kill something, I assume, Ken thought as he glared at the sky and put water into his ears and covered it with his hands as best as he could. The water would muffle the thunders rumble, so he didn hesitate to use it.
A huge boom rolled across the plain as Ken flinched. Although the noise was quieter last time, it was still enough to make his eardrums shake.
Right as the thunder stopped, Ken picked up his jian, which had completed its blood absorption, and waved it around while summoning water on its edge, ”What should I name this sword art? ” He thought aloud.
There were a lot of really cool – and fitting – names from anime he could think of to name his sword art, but he felt something original would suit his tastes more.
After a bit of thought, he announced, ”Splitting Tide. ”