Subaru had later returned with Rem to discuss a deal with Crusch, Anastasia, and Russell Fellow, merchant guild president, in a plan to take down the White Whale. While the meeting was shaky at first, Crusch accepted his deal, using her Divine Protection of Wind Reading to do so. 

"Divine Protections are really amazing though."

"Well, yes Natsuki Subaru. Though how do you know when the Whale will appear? You didn't mention anything about it."

Subaru decided to answer truthfully since he was working with Crusch he wasn't going to lie about how he knew she could just sense it, so he decided to tell her about Ki.

"Well that's easy, I can read it's Ki."

As Subaru said this he gained the attention of everyone in the room, even Rem was curious.

"Ki?"

"Yeah, you see Ki is a natural source of energy given off by people and objects when they move. It exists separate from mana."

"I see, and how does this Ki work?"

"Well, with the proper training, Ki-sensing can be used to predict attacks and others' movements, including natural objects and events found in nature. It can also be used to read peoples emotions and detect whether someone is lying or not."

The information shocked Crusch as well as Felix, and Wilhelm. They didn't know such a thing existed. But Rem was mostly shocked that Subaru could do something like that, she wondered if she could learn how to do Ki-sensing to.

"So since we are preparing for the upcoming battle I'm gonna go train. See you tomorrow."

With that Subaru left the mansion and went to the forest to train, as he made it to the forest Subaru only had two things in mind, to have better control of his anti magic and his Ki. And to find out how to summon the Anti Magic Swords. Subaru knew about the Anti magic swords he just didn't know how to summon them. That was his main goal.

"Ok in my dreams that white haired kid was able to pull the swords out of that same book, but people don't use those here they use gates and in my case it's different. I'm no longer human I'm a devil, not only that the book became a part of me so how am I supposed to do it?" 

Subaru at that moment came up with an idea, if the book was a part of him now then all he had to do was try to draw out that power. It would be the same as he drew out his anti magic, but this time he would try to summon the sword. 

"If I can summon that sword then maybe I might be able to do more against that damn whale, though I'm gonna have to focus really hard for this since it's my first time doing it."

Subaru already knew what the sword looked like, all he had to do was visualize it. As Subaru stretched his arm out, he closed his eyes and visualized. As he felt something in his hand he opened his eyes and what he saw shocked him. It was the same broad sword with the same black markings as before. 

"I-I did it...I finally did it! ALL RIGHT!!!!!!!!!!"

"Now all I have to do is make it disappear and reappear until I get the hang of it then after that I'll try to make it bigger and see what I can do."  

Subaru was training with the sword slashing trees and Mabeasts. All the while using the same techniques from his dream he remembered every single technique. All the while he was working on his Ki-sensing and anti magic control. For his Ki-sensing he would focus and sense for the movements of animals in the forest, and for his anti magic he would draw it out and coat it around his arm's making them black.

Subaru was training for 6 hours straight until he felt like it was time to go back to the mansion, as Subaru left the forest after getting his 6 hours of training in he made it back to the mansion. As he got there he saw a bunch of carriages and soldiers and a bunch of mages packing all kinds of things in the carriage. He met up with Felix and they began talking.

 After that they parted ways and Subaru went to his room and slept, while Subaru slept he had another dream he saw the same book but it was different the book had a clover with three leaves. Apparently the books were called grimoires and wherever it came from it was common but the rarest one of all was the 4 leaf clover grimoire. He also learned that there were three leaves of the clover that represented hope, faith, and love. And within the 4th leaf represented good luck, and within the 5th...DWELLS A DEVIL.

This left Subaru with so many questions. But before he could even think he saw the same white haired kid, but this time he saw a black haired boy. He was really tall and he had the 4 leaf clover grimoire. He also had a little fairy next to him, it looked like a fairy to be honest.

 But what he saw next shocked him...he became one with the little fairy as he grew a green crown on the side of his head. And pulled out a green sword, all of his attacks were wind based so Subaru came to the conclusion that he used wind magic. He was moving so fast that it would look like a blur to the naked eye, but as Subaru was watching this he also learned what it was called. Apparently it was called "Spirit Magic" which was a rare form of magic that allows the user to summon an elemental spirit to aid them.

 These spirits bond with and serve individual mages who have the same magic attribute as them. Each spirit possesses immense magic power and can increase their master's own magic power and spells. And in order to use this magic to its full potential, specific spells are required, which are stored within the grimoire.

 Seeing this reminded Subaru of a certain half elf as he remembered that she uses spirit arts with her spirit Puck, so maybe he could teach her about it after all of this was over. Subaru also remembered he has a high affinity for spirits so maybe he could tell Beatrice about this, maybe even by some miracle make a contract with her and teach her...if she was willing to that is. 

When Subaru woke up he sat down and took awhile to let all this information sink in. He knew he wasn't human anymore, he was a devil now so did this mean he had a devil inside him all the while being a devil himself? It seemed like that was the case but before he could think about it any further he looked at his right hand and noticed the same 5 leaf clover symbol was on his right hand.

"What the...when did it appear on my hand? Well it doesn't matter, if Rem or anyone see's this they are going to be suspicious of me. I better find something to cover my hand like a glove or something."

And right when he said that, he saw a black glove on the desk.

"Well speak of the devil."

He walked over to the desk and put it on his right hand and confirmed that it was a perfect fit. And with that he left his room and met up with Rem, They both greeted each other and went to meet up with Crusch and her army for the upcoming battle against the White Whale. Subaru and Rem had to pick ground dragons for the upcoming battle, Subaru picked a brown one and decided to name it Patrasche. The ground dragon apparently liked it's name as it allowed Subaru to pet it.

"Felix, I'll take this one it was love at first sight."

"Alright! but don't say love at first sight Subaru-kyun otherwise you'll make Rem-chyan all pouty."

Rem actually pouted at this statement.

"Rem is not, Rem can be nice to it!"

Rem intensely gazed at the ground dragon, now called Patrasche, and it was as if sparks were flying between the two.

After a boisterous meeting between Crusch and her followers. There they met more allies including a large demi human named Ricardo.

"Oho! So your the one who started this whole gig?"

"Are...are you with Anastasia's group?" 

"Yup, names Ricardo good to meet ya. You to little lady."

Ricardo patted Subaru on the back and left to go catch up with Anastasia. Later Subaru and Rem were on their way to Flugel Tree while he and Ricardo had a small conversation on the way there.

It was now nighttime and Subaru and Rem went of to go look at the giant tree in person while Crusch and her army got ready for the upcoming battle. Rem explained her belief in his abilities, and claimed that she had absolute faith in him.

"Rem..."

"Yes?"

"I told you that I love Emilia..."

"Yes...you did."

"But..."

He got close to her and looked deep into her eyes.

"But whenever I look at you, my heart flutters."

"Subaru-kun..."

"I just don't know Rem, I guess I like you to."

"...Rem doesn't mind being your second wife."

"I'll talk to Emilia-tan about it, if she's okay with it."

"Yes, Rem will do her best as well." Rem said with a now determined look on her face.

Later, before things were put into motion, they spoke to Wilhelm about his own purpose in this fight. He was fighting to avenge his own wife, Theresia Van Astrea, the previous Master Sword Saint, who was killed by the White Whale. He had been tracking it down for years now, and with Subaru's help, he had finally found it.

"Thank you Subaru-dono. With this, I may very well visit my wife's grave with my restored honor."

"Don't just thank me, I really didn't do much! But still, I'll do everything I can to help you take this bastard down."

Wilhelm shared a friendly fist bump as everyone moved to prepare for the ensuing battle. The time came as Subaru now had his eyes closed and he was just sitting there while Rem was looking at him wondering what he was doing, but that was when Subaru opened his eyes looked up and narrowed them. 

"It's here."

As Subaru said this his alarm went off. 

https://youtu.be/RSUs3L13Noc

All the soldiers and Crusch readied there positions. When they looked up that's when they saw it. The White Whale was towering over them as Crusch and all the other soldiers looked in utter horror.

The White Whale has appeared and the battle of the century was about to take place right at this very field.