Control 5

He started water walking in the middle of the lake and reached the centre. He took a deep breath and stood still on the water and started using wind on one leg to cool and the other leg to heat.

He didn't reach far when a hot wave pushed the cold water he made backwards, filling the area with hot water. Soon the cold wave followed.

He remembered how his papa didn't say anything about using clones and made 4 clones. They all separated on the lake, taking 20% of the lake each and started to apply Wind.

Natsu and Gray observed this while Gray made an ice clone, it melted soon because of the hot water as he needed to concentrate on maintaining it and decided to try alone.

Natsu didn't know how to make a clone and didn't bother doing it as he tried his best to heat the cold water. He didn't have any fire to eat.

Sirius on the other hand is trying different methods to achieve success. As he can use water style, he tried using water style to get a grasp, but even his second-level mastery in water didn't give him any edge.

As soon as he filled the area with normal water, new water will be released from the cave, dispersing the normal water he achieved and all his effort goes to drain.

As this was going on, Naruto was busy with Happy as he wanted the feline to improve himself and doesn't want him to be on the sidelines any longer.

"So Happy, tell me what can you do," Naruto asked the fish eating cat.

"Um, eat fish," came Happy's plain reply.

"That's it?" Asked a confused Naruto. Sirius was Happy's age and he can do a lot of things and always thinks of bettering himself. Happy was different. He shook himself from his thoughts.

"Ok, Happy. You can fly, right?"

"Aye, sir!"

"Let's test your speed and how much you can lift," said Naruto and Happy didn't seem interested.

"How about this, if you lift me, I'll give you some tasty fish I caught on my travels," said Naruto, pulling a fish from his scroll for added effects.

"Fishy?" He asked in a dreamy tone and upon Naruto's nod, gave him a salute.

"Good. Now fly with me," said Naruto and started Happy's training. He knew the poor guy is not a fighting type, so he is going to improve his support role as much as possible.

Time Skip: 15 days later

It's been 15 days since Natsu, Gray, Sirius and Happy fell into their training and they were doing it well in Naruto's eyes.

The lake was large as it has water coming from the river which was fed by the Sea nearby if there is any shortage.

He is impressed by their determination and will. They all endured the harsh environment they were in to better themselves and for the gift they didn't know in the case of Natsu and Gray.

The lake is at least the size of the Lake Sciliora in Magnolia which was clearly divided into 3 columns because of the continuous efforts of Natsu, Gray and Sirius.

Happy was supplying them with all the necessary food and covers whenever needed and he improved his speed and strength a lot in his training.

Before Happy could only carry one and a half Natsu's while now he can carry at least 5 Natsu's without difficulty at high speed and invented some new attacks as well.

Naruto saw him hitting the rock mid-flight as if to break it and cracks started to appear on the poor thing from his observation.

Naruto also trained in these 15 days in which he mastered switching between his light colours easily and managed to understand the thing in his necklace after a very deep soul searching.

He was about to go deep into his meditation when he heard a loud crack and looked at the lake where all three of them are working.

The cave wall started to crack. He had to continuously supply magic to the monster in the cave to keep it locked in and not come out and it seems his supply of magic is not enough after all these days.

Or the monster is craving some flesh to eat and hunt. Either way, he is confident that his students can take care of it without much effort.

The crack fully opened, revealing a large crocodile-like monster with rows and rows upon sharp teeth and a hungry and raged look on its face.

Steam blared from its nose and hot water started to release while its body started to release cold water which bombarded Natsu, Gray and Sirius.

But Natsu, Gray and Sirius were not paying attention to the monster as they developed a method to stay concentrated and not lose their concentration when a wave of hot/cold water is released.