An empty green plain that so wide, and looks peaceful, if not only for the titans wandering around

"So this is the Attack on Titan world" Shinji noted "as expected the air is really fresh!"

"Why we are going to this world big brother?" Illya asked

"To train Izuku of course!" Shinji said as if it was the most obvious thing in the world

"You are teaching him to kill Titan?" Ritsu asked, "I didn't see the connection with being a hero..."

"This is my first lesson for him" Shinji explained "before saving someone, you must save yourself!"

"I see," Illya said in realization "you didn't want for him to grow with Shiro- no my adopted little brother mindset..."

"I admired the selflessness of Shirou but that is not an easy way for a human to live," Shinji said remembering Shirou "As a hero, you have to save others but you have to remember, before saving other make sure you can save yourself "

"Shinji what happens if he dies?" Ritsu asked clearly worried

"I can just revive-" seeing Ritsu stares, Shinji quickly changes his answer "I will save him before he dies of course!"

"How about you guys go with Eri and tour this world?" Shinji awkwardly trying to change the topic "afterall the scene here will not suitable for a child at Eri age"

Ritsu continues to stare Shinji, only to sigh "Just make sure to save him before he dies okay?"

Shinji nodded hurriedly afterall even though he is stronger than Ritsu, in their little group no one has the most 'normal' human common sense except her. She literally the tie that anchored them to the moral of humanity to make sure their little group didn't cross a certain line that shouldn't be cross

Shinji group Human Common Sense Tier list

1. Ritsu [An former AI that developed sentience because of interacting with a class with a colorful personality]

2. Illya [A magus, with half homunculus blood, gained a basic understanding of normal human common sense because a class with colorful personality]

3. Eri [A victim of an experiment, most of the time locked away in a room]

4. Hinako [Required to learn it to blend in human society for years]

5. Shinji [Having understanding thanks to his past life but too much exposure to the Root breaking it, becoming magician didn't help at all]

6. Xiang Yu [Artificial Human that created to make true peace and his class is a Berserker, not really a common-sense material]

7. Arceus [Shinji familiar, as long Shinji order it to do something it didn't care for anything trivial like common sense]

Izuku POV

1 Hour ago…

"Okay, kid are you seeing that 3-meter tall giant? It was called titan!" Shinji sensei pointed at a sleeping titan, that somehow alone "and Titan love to eat human!"

"Your first lesson will be killing it, good luck!"

"…excuse me?!"

Back to the present…

Izuku currently planning to kill how to kill the titan, Shinji gives him a standard AOT sword that used by scouts and information that titan only can die if it slashed at the back of its neck

'I must not disappoint Shinji sensei!' Izuku determined 'and then I will become a hero!'

"As expected…" Shinji sighed seeing Izuku face, it was a determined face but if observed closely something didn't feel right "is not wrong to be determined but Izuku still thinking all of this as a dream"

For all his worth, Izuku is still a child with a history of being bullied. Even his favorite pastime is to deciphering hero quirks, sometimes he still reads and watches many wish-fulfillment stories.

For Izuku all of this is like a dream come true, meeting someone that can give him power that better than quirk, traveling to another world, and a chance to become the best hero.

All of that above is the perfect ingredient for a wish-fulfillment story.

Making Izuku getting a common SI disease. Thinking everything is gonna be all right, overconfidence, and a subconscious sense of superiority. He knows that this is a reality but still thinking it was his own story, a simple dream.

One of the reasons Shinji choose Attack on Titan world is to make a wake-up call for Izuku. Is better for Izuku to realize his mistake when Shinji still around to help clean the mess

The titan managed to detect Izuku before closing in afterall even most trained scouts can't escape titan instinct. Izuku is shocked didn't expecting the Titan to suddenly wake up.

"Don't worry the Titan is just 3 meters in height, due to its size it must be slow!" Izuku calmly analyzed the Titan "I just need run quickly to its backs when the Titan near me!"

'A mistake…' Shinji thought 'While his analyzing ability already showing its worth but his skill is Human Observation, not Titan Observation. Izuku will at least lost a limb'

In the end Izuku lost his right arm.

The Titan was too quick on its feet to the point Izuku didn't react in time because shocked at the Titan speed and accidentally stabbing the titan on its chest. He is caught by the Titan and almost having his head chopped off by the Titan bite if not using his right arm in a panic to hold the Titan jaw.

At that moment the Titan bite, Izuku scream echoed in the vast plain.

As protagonist Izuku didn't lack determination even his chopped arm still aches enough to bring him to tears, with his quick thinking Izuku uses his remaining arm to pull the sword that stabbed on the Titan chest and using it to stab Titan neck penetrating right to the back of its neck.

It managed to hit the Titan vital point taking the Titan down.

…

"So do you know what did you do wrong?" Shinji asked Izuku

"I am weak…and overconfident" Izuku stared down didn't dare to look Shinji in the eyes, his the remaining of his right armis wrapped in bandages "I think all of this just like a game, a dream, and didn't take it seriously"

Shinji smiled "Its a good thing you are learning. If you didn't learn and whining or blaming yourself about didn't have a quirk, I will need to throw you into OPM world to meet with Mumen Rider"

Izuku didn't know about the OPM world but guessing from Shinji word, that world must have a quirkless hero. And a famous one at that

"Here, let me regrow your right arm" Shinji offered

"...sensei, I think I will keep it as a reminder of my stupidity," Izuku said still feeling the pains "afterall it was a really valuable lesson that I didn't want to forget"

"..."

"...because your next training needs 2 arms to works, I will give you some prosthetic arm" Shinji stared at Izuku "the offer to heal and regrow your arm will open until the end of your training"

"Thank you Shinji sensei" Izuku thanked

"You are dismissed" Shinji shooed Izuku away "go play rest or something"

With that Izuku went to his tent for resting...his tent is full of All Might merch...

...

"Arceus!"

'Yes, Creator?'

"Please create some gold, silver, iron, mithril, and, steel" Shinji ordered "I want to make a prosthetic arm…the best kind"

In Shinji mind the blueprint of a prosthetic arm ready to be used.

"Lets make the prosthetic arm worthy of god! The Silver Arm - Airgetlam!"