Hyoudou Issei, 7 years old, was sitting on the empty swing and swinging, her only friend Irina had gone to England, and she didn't seem to be coming anytime soon, unfortunately there was no one in her neighborhood who could be friends with her at the same age, which inadvertently caused her to feel lonely. As he was wandering into the house, he suddenly felt a sudden pain, his left hand hurt incredibly. When Issei looked at his hand, he unreasonably saw a red glove with a green jewel in the middle, which covered his whole left hand, and there were golden scales at the end of the glove. Issei was slightly shocked and wanted to take the glove off. But unfortunately he failed, he ran home with all his might, but when I got home, the glove on his left hand had already disappeared. When he told his family about the situation, his mother thought he was sick and sent him to bed to rest. N was perfectly aware of what he could and could not do, he calmly fell asleep dreaming that Irina had never left Japan and was playing with him just as he was about to poke Irina [Looks like you're having fun, shitty brat] A mysterious voice echoed inside Issei's head.

A low and expressive voice. It was an unfamiliar voice, but somehow he felt like he knew Issei. A voice that is always close to him…

[True. I was right next to you]

…Who is this?

Issei was looking around, and the park was nowhere to be seen at the moment.

Irina, who was with her, also went

Or rather, where was it? She had lost all her senses.

The front was pitch dark. She couldn't hear anything with her ears. Silent.

…What is this?

Mom! Dad! Irina!

He was screaming the names of the people he was close to in his heart, but there was no answer. What's going on with me?

Whose voice is this?

[This is me.]

Wow!

The sound didn't come out of Issei's mouth, but she really was in shock in her heart.

Certainly. Everyone gets scared if a huge monster appears in front of them.

He has big eyes. His eyes are red like blood. A jaw that went up to his ears, with a lot of sharp teeth sticking out of it.

He had a thick horn lined up on his forehead, and the scales covering his body were red like magma.

It has thick arms and legs like those of a giant tree. The claws look very sharp and scary.

Moreover, its spread wings make this giant beast look even bigger.

In front of him…a giant monster…and of all that he knew, the one that most resembled him—.

-Dragon.

It's as if Issei knows what he's thinking even though he can't speak, and the beast standing in front of him raises a dragon's mouth a little.

[Really. Correct point. I've been trying to talk to you the whole time. But my words have not reached you until now because you are so weak. Finally. I was finally able to appear before you.]

…What does this creature say? Issei did not understand.

Has he been trying to talk to himself all this time? He didn't know. He didn't know that! What? Was he trying to eat her?

[Food? Would he eat you who looked awful? Like I do. This is not it. I just wanted to introduce myself to my partner, whom I will fight alongside from now on]

Partner? Wait a second. He didn't even know what he was talking about!

Dragon! Who are you-.

[You already noticed, right? You've probably thought about it. Yes that is right. I am exactly who you think I am. Let's talk again. Yes, partner.]

When Issei looks at her left arm, it is covered with red scales and looks very abnormal because it has really sharp claws.

10 YEARS LATER

I am Rias Gremory now I am urgently summoned to my real home, Gremory Mansion, so I leave my work in the human world unfinished and pass through the teleportation circle, the moment I pass through the circle, I find myself in front of my father in the Main hall of the house. He seems to want to talk to me about something very important. His father suddenly started talking, "Rias, it is very important that I have to tell you. There is a subject"