High School DxD Volume 2 Chapter 5.2

Red——. I'm having a red dream.
Something makes a sudden complaint to me within myself.
It's saying that the power I am using now isn’t its real strength.
Who said that? The Sacred Gear? Something which is inside me?
He moves its lips while shaking its scorching fire.
[If you are like that, you will never get strong.]
I hear something like that in my mind.
It's not something I thought inside my head. It came from deep within my heart...... No, it came from my left arm......
[You are an abnormal being who possesses a Dragon within you. Don’t show such a miserable state. The “White guy” will laugh at you.]
Are you that Dragon that appeared in that dream? Was that new power up because of you?
[Yeah, that's what you desired, what I desired, and what the “White guy” desired. That’s why you went into a new phase.]
Desire? What are you saying......?
I mean who the heck is the “White guy”!?
[He will appear before you sooner or later. Yeah, he and I are destined to fight. Oh yeah, by the way, it's about my power. I will teach you how to use its real power.]
What are you saying?
......What on earth are you......?
[Welsh-Dragon, Ddraig. Hyoudou Issei, I’m the one inside of your left arm.]
Welsh-Dragon......Ddraig......
[Losing may be all right. If you don’t die, losing can become your strength. However, it only means something if you win the next fight. Lose then win. Then continue to win. If you do that, you will meet him.]
So what’s going to happen between me and “him”......?
[You will know soon enough. Get stronger for that coming day. I will give you my power any time you want. However, keep it in your mind that it will come with a sacrifice of something great. I will give you something that is worth the sacrifice. You can show it to those who laughed at you. The existence of a “Dragon” that is.]