Eren tried his best to sleep, but no matter how much he tried, it was never able to. During the Rumbling, he killed many Eldians as well, Eldians who lived outside the walls. Since the Founder was connected with all the Eldians he had memories of them…their families…their emotions…and their lives with the people of the world. He heard their screams of terror as they were under the feet of the Wall Titans, seeing their doom. He tried to think of anything happy in his life, but he never found anything…not even one single happy memory. He tried to think of his mother's loving smile, but his mind then went to the day she was eaten by Dina and then years later when he masterminded the whole thing. He felt even more restless. He then thought of Mikasa, all them she saved him as a kid and a soldier. He thought of the little vision of a peaceful life they had before she killed him. He felt warm as he knew she would be safe, but then the realization that she will find another man to be happy with began to make him cry. Although it was painful, he still continued to think of that as he had near to no happy memories to begin with, and he had more chances to sleep in sorrow than in anger and guilt.

Eren got up very early, almost two hours before training. He got ready, tied his long hair in a bun and donned his uniform. He wore a blue undershirt, a white shirt with blue stripes and blue trousers. He then left for the Academy. As he walked, he heard people whispering behind his back. He didn't pay much attention to them as his head had put him through worse. Soon, he reached the entrance of the academy. It was a huge multistorey building with architecture similar to that of the architecture of the other buildings in the city.

"These people surely have weird buildings. I feel like I'm on another planet." He slowly said as he looked at the structure in front of him.

"That's strange." He heard a voice next to him. Eren then suddenly turned to see a short young man with spiky white hair with bangs next to him, looking at the building. He had a captain's white coat on him

"You…You're one of the guys who supported me during the trial!" Eren recognized him

"True. I supported you on a benefit of doubt, so it's better you show me some respect."

He then brought his hand out to him

"Captain Hitsugaya."

"Umm…nice to meet you." Eren brought his hand out to shake it

The two then looked back to the building and he continued

"So you've never seen this kind of a building before?"

"No. Not even once."

"What about in a picture or a drawing?"

"No. Never. This is the first time I'm seeing this. It feels…alien."

"I see. So you'll be starting your first day now, right?"

"Yes."

"*sighs* I don't know why you chose Kuchiki Rukia of all people to be your sensei but I'm warning you…I've seen her, Yoruichi and a few others make an impossible training regiment for you that even our toughest guys can't crack. It can kill you if you go through it. I don't know why I'm doing this but if you feel like leaving her, I'll be ready to take you under my wing."

Eren slightly smiled and said

"I really appreciate the offer, but I doubt it will come to that."

"Try saying that after you go through her regiment."

He then gave a confident smile. Toshiro knew what he meant, but he never understood it. It was the same smile he had when he laughed at the mention of hell…like all of it was child's play compared to what he had seen in his life. The two then parted ways and went to their own tasks.

Rukia woke up grumpily that day when the thought of her personally training Eren came to mind. She became even more irritable when she saw Eren report earlier than her for training with a smug look on her face. However, she kept herself from losing control as she was sure that she would make him literally run for hell with her training regiment. All she had to do is wait.

He everyday training firstly involved combat training (Hakuda) under Soi Fon, who proceeded with teaching advanced techniques in the first instance with many reps without starting with the basics. These techniques were extremely hard to do and reduce one's morale if done without the basics. They're also very dangerous and one wrong move could lead to injuries that take time to heal. And Eren made a LOT of wrong moves, causing him many injuries. But despite this, he was still able to stand back up and fight. Keeping aside the fact that he was someone she hated, Soi Fon was really impressed by his will power. Even so, for all the training she put him through, he was to scream in pain at some point or the other. But he didn't. He grunted and heaved at points, but never screamed. It was either of two things: He was inhumanly resistant to pain or he had incredible healing abilities, both of which could be bad news to any opponent he faces.

Eren's second and last part of his training for the time being was Zampacto training (Zanjutsu). For this, he was taught by Unohana. Although Rukia taught him the basics, Unohana mercilessly went about him with spars and fights after that, leaving him with multiple scars. She even used to coldly mock his lack of strength with a smile on her face…something Eren particularly hated about her. Initially he wasn't able to keep up with only one sword in hand. After a few weeks, he changed his style to use two swords instead of only one. Soon after, he was able to improve his skill with this small change. This intrigued Unohana, and even Rukia to an extent. In usual practice, people become proficient in using two swords only when they are very effective in using one. But this man was the opposite. He became more proficient in using one sword after he mastered wielding two of them.

The other two parts of his training, Demon Arts (Kido) and Fast Movement (Hoho) were to be taught in the next three years. But for now, he'll have to master the first two skills.