As the Gremory peerage train for their fight against Riser Phenex, Yukio comes to know Rias' Pawn, a boy of his grade names Hyoudo Issei.

"Come on Yukio, we're almost there" - Sona commented while she and Tsubaki ascended the mountain.

"Yeah, I know, but.." -

"Is there a problem?" -

"Why was I made to carry your equipment!?" -

"You are phisically stronger, its only natural" -

"I'm pretty sure that's not the case" -

After a few minutes of more walking, they arrived at the top of the mountain, finding the Gremory alredy there.

"I was almost thinking you wouldn't show up Sona" - Rias said.

"Sorry for the delay, Yukio took a bit too long to wake up today" - Sona answered with slight annoyance.

"I'm a heavy sleeper, sorry" -

"Well, whatever the case, we're alredy here. Do you have a specific training in mind?" - the student council's president asked.

"Not anything specific, we were simply going to train our abilities i matches, would you like to join us?" -

"I'm not much of a fighter myself, but it will certantly be interesting" - Sona said, before thinking of something interesting - "Rias, how abou 2? You and Issei versus me and Yukio" -

"King and Pawn fighting together? You made this more fun Sona. Issei, come here, let's show them the might of the Gremory family!" -

"Yukio, to me, help me prove the superiority of the Sitris" -

The 4 took place, preparing for a fight that would be spectated by the remaining members of both families. Wasting no time, Yukio used Trickster's Fantasy, summoning his armor while Issei summoned a gauntlet at the cry of a loud "BOOST!".

"That is a Sacred Gear, Boosted Gear, be careful with it, it has some hidden tricks" - Sona warned her Pawn.

"Understood, I'm ready to fight" -

The first to made a move was Issei, who launched a powerful energy beam from his gauntlet called Dragon Shot that Sona barely managed to avoid. She responded by summoning 3 spheres of water, then turning them into spikes.

"Advance, I'll cover you" - she whispered to Yukio.

Her Pawn obeyed, launching a frontal assault while the spikes from Sona intercepted some of Rias' own projectiles which were fired against him. He appeared directly in Issei's face, barely giving him time to cover before being punched by Yukio's claw and being pushed back a few meters.

Rias didn't took this lightly as she fired several rounds of her signature Power of Destruction against Yukio, which he managed to block yet still suffered some damage. Sona countered to this by summoning water tentacles to grab Rias before slamming her into the ground.

Yukio saw this and tried to hit Rias as she was defensless, yet Issei got right up in his face and punched him as payback for his earlier attack before firing a direct Dragon Shot at him, which Sona blocked with a wall of water yet her lack of concentration on Rias allowed the red devil to break free and attack both of them.

While Yukio had an easier time resisting the attacks of both due to the power of Trickster's Fantasy, Sona was suffering more from the attacks, so Yukio decided to use himself as a shield to defend his King while she recovered.

As soon as the Sitri managed to get up on ver feets, she summoned 2 geisers underneath them, sending them flying.

"Gonna be real here Sona, not exactly what I was expecting, my arm hurts also" -

"Power through the pain. I have an idea to take them down, but I need you to follow my instructions perfectly or else it won't work" -

"Alright. I'm not so good at following orders but I think I can try" -

"We'll train that later. Now, first of all, can your flute do..." -

As Rias and Issei descended onto land once more, they saw Yukio with Trickster's Fantasy in his hands. The boy then started to play a song in it, but this time it was different, it was a more agressive tone. Hearing it made both Issei and Rias fall to the ground wile covering their ears, the music was causing them pain.

"Good, keep them like that Yukio!" - Sona said as she used her powers to generate 2 giant water serpents that entangled around both of them before slamming them into the ground with enough force to creat 2 big craters.

In those, Rias and Issai layed, barely able to move.

"Sona Sama, Yukio San, you did it" - Tsubaki said calmly, yet she changed to fear when she saw how both of them fell, nearly unconscious - "Are you alright!?" -

"Y-Yeah, it's just that... I don't know why, but holding that transformation for a while ends up hurting me, having to play to keep those two defensless only increased the pain" - said Yukio.

"Same here... That trick with the Serpents drained nearly all of my energy... Haha, what a waste" - Sona said as she tried to get up.

Tsubaki tried to get both of them up as the Gremory family got Rias and Issei back up. After helping them recover, Issei wanted to test Yukio's abilities i battle, which the boy despite being still a bit tired agreed.

Both of them got into fighting position as Yukio once more summoned his armor, with Sona noticing how he was slighty sweating. As they charged against the other, a water projectile was fired from the sky and nearly landed on both of them.

"What the?" - Yukio said as he looked at the sky, yet nothing was there - "That attack..." -