I'm Diego, I'm 17 years old, I was a big Otaku, I watched a lot of anime and I always dreamed of one day going to an isekai. 

Diego: Where am I? What happened?

Diego: Uh, I remembered, I was robbed, I resisted and I died...

Diego: My family, my mother, I will miss them but I want to see them again, at least one last time.

Unknown Voice: Hello Diego, your family will be fine, for the people who come here I will give them an option just for them.

Diego: Option?

Diego: Go on, what is that option?

Unknown Voice: The option is that all the people who know you, do not notice that you die

Unknown Voice: In short, everyone will forget you 

Diego: Uh... I accept.

Unknown Voice: Okay, correct option, Now, you are going to be reincarnated, in a world, in your world it was known as High school dxd, Obviously I know that a human like you would die quickly, so I decided to give you a gift that you will discover, and your appearance will change, you will take the place of someone who is already there, But don't worry, he's already dead, he died of a heart attack.

Unknown voice: Do you agree to go? Or do you want to continue a pathetic life in the sky, sunbathing all day?

Diego: I accept, I accept to go to the world of High school dxd.

Unknown voice: In three seconds you will pass out and you will be there.

Diego: I'm already in my new world

Diego searched through all his clothes to see if he had Kuo's student clothes, and when he didn't, he searched the internet for Kuo School.

Diego: Well, later I'm going to go to school to enroll, first I'm going to prepare my breakfast.

Diego stood still remembering that they told him he was going with a gift.

Diego: What gift did he send me with me?

Diego: A system? A power to be the strongest in this world?

Diego He started trying to use all kinds of skills, he tried everything from jujutsu Kaisen, Naruto, Boku no hero, in short, all the animes he knew.

Diego: It's getting a bit late for me, I'm going to go now.

Diego arrived at Kuo school, went to the director to see if he could enroll and how much money he needed.

After talking to the director, and checking how much money he needed and if he could get in.

Unknown voice: Sorry, Diego, I forgot to send you money, don't spend anything, absolutely none of the money in this bag is exactly counted, if you spend a little they won't accept it.

Diego: Okay

Out of nowhere a large bag appeared next to Diego.

Diego: Wow, there's a lot of money, but I can't spend any of it, I guess it pays me for a few years. 

Diego: Tomorrow I'm signing up, today I'm going to train, I have to train and not be an Issei 2.0

Time lapse one day:

Diego: Yes! I'm already at school, next week I can go, now I'm going outside because I'm bored.

Diego, when he was looking at the whole city, passed by an alley, and saw a thug threatening a child.

Diego: I don't want to get into trouble, what if he has a knife, it will solve itself.

Diego: Who am I kidding, I'm going to help him 

Diego silently approached the thief and put him in a hold.

Diego: Run kid, I don't know how long I can last.

Thief: Krr, let me go, damn it.

The thief managed to free himself from the key and punched Diego in the face.

Diego: damn.

The thief began to beat Diego.

Diego: Shit, I can't do anything. Will I die here? Shit, I didn't want to die so quickly.

Suddenly Diego began to see the world slow down, he saw a blue energy in the middle of the thief, he recognized him.

Diego: Jujutsu Kaisen, six eyes, hehehe

Diego began to see all the movements of the thief and gave him a contract that was in his face

Thief: Agr, Damn

Thief: Stop, please.

Diego: Alright.

I better go home, I already have some of his belongings, I'm going to sell them.

Diego: I finally got home, my body hurts, but now I have to learn to manipulate the cursed energy, I'm going to spend all night practicing it.

Time lapse of a day:

Diego: Ah, I'm very sleepy, but at least I know how to make it flow, now I must learn to use my cursed ritual, if I have one clear.

 Time lapse of 1 hour:

Diego: Finally! Finally a small blue one came out, it didn't take me long, now I just have to shape it, how much cursed energy it has and its spatial attraction.

Diego: I'm going to train all day now to practice my blue and activate infinity.

Time span of a day and a half:

Okay, I'm going to hunt demons.

I searched all afternoon but found nothing, until at night, in a container, I saw one.

I quickly approached him and attacked him with a knife that I had, but the knife broke.

Demon: Hehe, naive do you think that simple little toy can do something to me?

The demon threw a quick punch towards Diego's face but he dodged it with difficulty.

Diego: Damn, I can see his movements but my body can't keep up with me.

I raised my hand and threw out a medium-strong blue.

Demon: Ugh, damn, but that's still not enough.

The demon attacked me again with his fist but this time when I dodged it he hit me with his tail.

Diego: Agh, how did he defeat him?

Diego: I know, I'm going to use infinite, the bad thing is that I can only use it for a few seconds.

Devil: You talk to yourself so much, huh? Are you already seeing your whole life pass before your eyes?

Diego: No!, I just know how to kill you, Bitch.

In an instant I appeared in front of the demon and kicked him, because of infinity I can now damage him more with punches.

I kicked him in the stomach again, he fell back and I waved my hand in his direction.

Diego: Blue!

Diego: Phew, thank goodness I don't see it, I thought I would have had to use all my damn energy.

Diego: Shit, here it comes, agh my cheek, she scratched it with her nails.

Devil: Impertinent human, you need a thousand of yours to kill me, now you are going to die, before he was distracted, now he is not.

Diego: 1000?, nah just one is enough.

Diego: 100% Blue!

Devil: AAAAGHH!!!!

Diego: Finally, what the hell is wrong with me? What's in my stomach?

The next moment something exploded in my belly, leaving large wounds and destroying most of my polo shirt.

Diego: Shit, it hurts so much, I better go home.

Devil: Where do you think you're going?

Diego: Shit.

The demon punched me hard in the stomach, I fell onto some rubble.

Diego: Shit, I can't die here, I'm going to finish this demon.

Time span of 1 day:

Diego: Ugh my body.

Diego: I regretted it a little, Going to hunt demons.

Diego: I'd better stay training all these remaining days.

Time lapse of the remaining days:

Diego: Ah, I have to go now, it's late dammit.

I ran out of my house to school.

Diego: Yeah, I finally arrived.

I entered the school and was looking for my classroom.

Diego: Ready here is my classroom, I was in Issei's classroom.

I knocked on the door and the teacher came out.

Teacher: Excuse me, what do you need?

Diego: Hello, sorry for the delay, I'm new and I'm from this classroom.

Teacher: Okay, give me a few seconds and I'll call you in, introduce yourself and sit wherever you like.

A few seconds passed and the teacher called me.

Diego: Hello good morning to all my classmates and my teacher, I'm Diego, Diego Browns, I am 17 years old.

I went to sit next to Issei, he just looked at me, but I was thinking about how I was going to handle the whole story.

Did I kill Issei? Or do I not kill Issei?

I took off my glasses to check something and it was just as I thought, I can see the energy of the great red emperor separated from that of Issei, I already knew what to do.

At rest:

Diego: Hello, as you well know, my name is Diego, what is your name?, nice to meet you.

Unknown: Issei, nice to meet you too.

Diego: Hello Issei, Nice to meet you, I hope to be a good friend of yours.

Okay, it's time to decide. Did I take the Emperor Dragon from him? I just checked when I got closer. I can do it. I just have to control the cursed energy better.

Yes, I know, I know, I may sound a little hypocritical when I say "I hope we're good friends" But come on, this is not an anime anymore, it's my real life, I have to see how to develop this story without a pervert fucking with me.

It's also more than clear that I want to have a girlfriend, now yes.

I felt someone watching me, I turned around and saw her, I saw Rias Gremory looking at me through the window, I just looked into her eyes and walked away, I already knew what to do.

When I got home I started training my cursed energy, the next day I was going to hunt fallen angels or demons.

Time span of a day and a half:

Diego: Shit, he's strong, this fallen angel.

Diego: Blue

I moved quickly and threw a strong punch influenced by infinity, I was doing something to make my infinity last a long time, I was doing the same thing as Vegeta in the Black saga of the manga, I was interspersing my infinite and non-infinite to save more of my cursed energy.

Fallen Angel: Stupid ape, you're not going to beat me, I'm superior to you bitch!

I closed his mouth with a punch wrapped in infinity, and I gave him a blue face all over his belly, finishing it off.

Diego: Ugh, this is becoming easier and easier for me. I've already finished off two demons and three fallen angels. That's enough for today. I'm going home.

When I got home I started training my cursed energy until I fell asleep, the next day I woke up earlier but to train and try to remove the cursed energy, Or at least try to feel it with that they will already lay the foundations to take away Issei's sacred gear without killing him.

I managed to touch her, a little more practice and I'll take off her sacred gear, now I have to get ready and go to school, When I get home from school I have to start training.

Diego: (I have to keep training, I can't rely only on the Infinity and the Six Eyes. If I want to take the Boosted Gear, I have to be able to fully control my Cursed Energy and unlock

My body was still aching from the last fight against the fallen angel. I had made great strides in controlling Infinity, but I still couldn't use it continuously like Gojo. The problem was clear: My cursed energy did not flow so precisely.

Diego: (If I keep training like this, it will take me weeks to achieve it… I need a more efficient method.)

I sat on the floor of my apartment and closed my eyes. With Six Eyes and observed my own body.

The energy was flowing well, but when I tried to reverse it to heal my wounds, it would collapse within seconds.

Diego: (Tsk… Cursed Energy is negative by nature. To turn it into something positive and achieve healing, I need to collide it and stabilize it… Like Gojo did.)

I spent hours repeating the process. Every time I failed, I tried to adjust the flow.

It was dawn before I knew it.

Diego: (At least I made some progress… But I still can't regenerate like Gojo.)

My body was exhausted, but I had to go to school.

I got ready and went out.

Upon arriving, I saw Issei with his friends in the hallway.

As usual, they were talking about perverted things.

Diego: (I'm not surprised... but I still find it pathetic.)

Ignoring them, I went to my classroom and sat down.

As the teacher spoke, I activated the Six Eyes and began to analyze the energy flow of those nearby.

Diego: (If I remember correctly... here at school there is another student with a Sacred Gear: Saji.)

Saji wasn't in my class, but I saw him in the distance.

I focused on his arm and noticed something interesting.

Diego: (There it is... The energy of his Sacred Gear is fused with his body. Unlike the Boosted Gear, which is an artifact housed within Issei's soul, Saji's is more of an extension of his own soul.)

I watched his energy for a while, until it was time for lunch.

When I saw Saji walking away from his group, I followed him discreetly.

I approached him and spoke to him.

Diego: Hey, you're Saji, right?

Saji: Yes, and you are?

Diego: I'm a new student and I came to look for interesting people.

Saji: Interesting?

Diego: Yes, like your arm

I understood the hand and lightly patted him on the shoulder, pretending it was a simple friendly gesture. 

Diego: (Okay… I already touched on it. Now I can analyze its structure in more detail.)

Thanks to the Six Eyes, I was able to see exactly how his Sacred Gear worked.

Diego: (I understand... His Sacred Gear is a type of parasite that is fused with his energy flow. If I want to do the same with Issei's Boosted Gear, I will need to break the link between the wearer and the sacred gear, Before you can take it.

Saji: Why so much interest in my arm?