The Protagonist's Sister Is Actually The Strongest

The capture of Astaroth’s Soul was a combination of many existing factors and a few others I made real through Skill Fusion. Thanks to Sepa’s Soul Manifestation, my own Cosmic Energy, my Arcane Hands “hacking” through the composition of his enormous soul, and the combination of spells weakening and sealing its true powers, all while Gram was able to weaken him severely and then create the Purgatory Realm Skill, they were all factors that made this enormous victory possible.

It’s not like I know every possible Skill Fusion out there, but as my Stats increase, I can see and feel insights. Sometimes, by just thinking about it or theorizing an idea, I can see what the results of Fusions could become. This “Insight” is both the effects of the Divine Eyes of Truth and probably a few other Skills as well as my Stats.

Of course, the memories of having read the novel help tremendously too. Although my brother never had Divine Eyes of Truth, he has the innate ability to combine Skills through the Gluttony Skill that Fenrir gave him.

Therefore, based on his own Skill Fusions, I can draw certain conclusions about which skills can be combined to create different types of new Skills. And, well, it’s always important to make sure they make sense.

For example, Healing Hands and Great Sorceress would obviously give me some sort of hand that could conjure a lot of magic, and also, the essence of Ramses Urn, which can trap and seal souls, with the divinity of death of Thanatos Stigma might have given me the way to seal a powerful demonic soul with a fragment of a God of Death’s Divinity.

And it worked!

“Get me out of here! Y-You can’t just do this! The other Apostles of Death will not forgive you! And the Constellations backing me…! They will keep hunting you, you damned human!” Astaroth kept barking furiously, but he was too tiny and pathetic for me to feel intimidated.

“So you really trapped him there.” Sara glanced through the Purgatory Mirror, which allowed her to see what was happening inside. “This bastard that killed me... Heh, good, this is a fitting punishment! Killing him would have only given him the chance to come back in another vessel anyway.”

“Yeah, I can’t kill him right now, but I was able to seal him.” I nodded. “Now, Sara, how about you have some fun?”

“F-Fun?” She asked curiously.

“I know you have a terrible grudge against him, and this is just not enough, right? Also, you can get used to your new abilities and... well, accept what you’ve become much better at if you have an unkillable dummy like him.” I smiled. “Wanna give it a try? Just a couple of minutes so you can let out some steam.”

“Anna…” Sara suddenly felt surprised by my words.

Of course, I wasn’t talking about this without any point; I knew based on the background information I got from her after giving her some privileges that she was struggling with accepting what she has become and also with the terrible grudge she has against the one that took her life.

If we let her torture Astaroth to her heart’s content, she might get over this quickly.

“So?” I asked her with a smile. “Wanna give it a try?”

“But we’re in a raid, and... Ah, screw it.” Sara instantly jumped into the Purgatory Realm Portal, which Astaroth tried to immediately use to escape.

However, no matter how much he tried, an invisible wall stopped him from coming out. Unless I allowed him to get out, he was never getting out of there.

“ARRGGH! Why can’t I get out?!”

“You’re coming with me, bastard.”

Sara grabbed him by the neck and threw him down into the Purgatory. I allowed Astaroth to regain his large dragon form because torturing a tiny little snake would be boring and pitiful.

“Y-You dare come to confront me alone?!” Laughed Astaroth. “Your friend has committed a terrible mistake by giving me back my form and strength! I’ll crush you to- Geh?!”

CRASH!

However, a giant fist made of phantasmal energy threw him several meters away, creating a gigantic fissure right where he landed. The Purgatory Realm seemed endless, but it wasn’t larger than a stadium, and that was enough space for the two to fight to their hearts’s content.

“I didn’t know I could do this…” Sara looked at her own Phantasmal Aura, which had shapeshifted into a gigantic arm with a fist. “So this is how it works, huh? Not just clones; what else can I do with this power?”

She smiled, looking at the furious dragon slowly standing up, his body engulfed in Black Flames, his many eyes glowing bright red.

“YOU BASTARD!!!”

He rushed towards her, unleashing an endless rain of black flames and fireballs towards her. Numerous explosions engulfed her.

BOOM! BOOM! BOOM!

“Hmph!”

However, Saran quickly rushed forward, her body transforming, as she used her Spectral Body Skill much better, generating several arms and then skeleton-like claws!

CLASH! CLASH! CLASH!

“Amazing…! And there’s more to it too! I can shape this however the fuck I want!”

Sara laughed manically as she reached Astaroth, kicking his giant head several times with her hard black heels, making him scream in agony before several spears made of phantasmal flames pierced his body several times.

“Urgh…! W-Why are you so damn strong now?!” Astaroth screamed.

“In this world, Astaroth, the stat boosts from your sponsors don’t apply.” I smiled. “Also, your soul is sealed into a tiny ball, so you can barely use around… 25% of your true power?”

“THIS IS UNFAIR…!”

Astaroth kept crying as Sara happily beat the shit out of him constantly. Meanwhile, I checked the new Skill’s information before beginning to analyze my surroundings.

-----

[Divine Demon-Sealing Purgatory Realm (SS): Lv1]

This tale has been unlawfully lifted from Royal Road. If you spot it on Amazon, please report it.

[Skill EXP]: [0/25000]

A Unique Skill created by the Fusion of the Essence and Power of [Ramses’ Soul Eating Urn] and the [Thanatos’ Stigma] Skill.

A Special Pocket Dimension was first designed by the Ancient True Archangels to seal the powerful Demons that couldn’t be sealed with normal Celestial Magic.

This special Realm that is not larger than a stadium can seal any Demon Soul within, a Purgatory for their sinful souls. The more sinful their souls are, the more sealed their powers become.

The wielder of this Skill can invite anybody inside to open a {Purgatory Portal} whenever they please and see inside of it even without opening one through the {Purgatory All-Seeing Eyes}, while also being able to show its contents to others through the {Purgatory Mirror}.

Demon Souls sealed inside the Purgatory cannot do as they please independently and will be below the Skill user’s authority until the day of their deaths, or until they free them willingly.

Even when outside the Purgatory, the Demon Souls will always belong to the wielder. And through {Demon Soul Synthesis}, it is possible to transform the shape of the Demon Soul and the body attached to it, if there are any, into many shapes, such as Weapons, Materials, or even Beasts and Humanoid forms by supplying with Mana and Demonic Energy to the Demon Soul.

When using the Demon Soul in such ways, the Master has total power over their abilities. The Space within the Purgatory expands as the Skill Level increases. The Purgatory might develop an ecosystem of its own the more Demon Souls are placed inside, giving further strength to the Master.

Each Demon Soul sealed inside will have 25% of their Stats shared with their Masters, along with some of their Abilities and Unique Powers, which can be activated through the {Purgatory Soul Fusion} Ability, for as long as 1 Hour. Cooldown: 5 Hours.

Level Bonus (1): Purgatory Space +10%. {Purgatory Soul Fusion} Durability: +10%. {Demon Soul Synthesis} Super Rare Transformation Chance: +10%.

-----

A very strange, if not bizarre, skill... It allows an incredibly great deal of freedom in what I can do with the prisoners inside. Although that little bit of lore about Ancient True Archangels is new to me. I guess this Skill might be possessed by very powerful Constellations.

And I can do a lot with Astaroth’s Soul, much more than I had previously thought. I could even turn him into material! Or, maybe, a weapon? Or another pet, or all of them at once! Oh my, he sure has a lot of styles.

As Sara beat the crap out of him, I started to gaze around my surroundings, feeling that we were still trapped within the Pocket Dimension.

“So killing the guy doesn’t fix it?” I wondered, gathering the leftover materials for Astaroth.

Because she shredded his body so much, there were a lot of goodies left behind. Including a lot of strange divine spiderwebs, huge spider legs, bones, flesh, organs, blood, eyes, and skull pieces, all of which were quickly gathered inside my Inventory.

Ding!

[You have gathered: [Astaroth’s Aberrant Arachne Legs (A- Rank)] x8!]

[You have gathered: [Astaroth’s Arachne Divine Spiderweb (A+ Rank)] x22!]

[You have gathered: [Astaroth’s Corrupted Draconic Blood Bottles (S- Rank)] x17!]

[You have gathered: [Astaroth’s Degenerated Demonic Internal Organs (S- Rank)] x9!]

[You have gathered: [Astaroth’s Broken Draconic Bones (S- Rank)] x16!]

[You have gathered: [Astaroth’s Demonic Dragon’s Eyes (S Rank)] x4!]

[What Luck! All Items Ranks have increased by one!]

After gathering all those goodies, I quickly decided to start working.

[“Oi, are you not going to share some of that?! I’m starving here!”] Gram complained.

“Later, and you can’t even feel hunger, you’re a sword.” I laughed. “Now, how about we break out of this dimension? I bet that Imp will keep throwing demons at us once he sees Astaroth is nowhere to be seen… Although I would love more EXP, there are more important things to do right now.”

I imbued Celestial Energy and Demonic Energy into Gram’s Blade, alongside some Cosmic Energy as well, and then activated [Thousand Blades]!

“RAAH!”

With a roar, I swung my sword several times against the empty air in front of me. Several slashing blows pierced through something, and Gram’s blade was constantly slashing the empty air.

Crack, crack…!

Until cracks started to appear, constantly...

It was working as intended. Good!

“Keep going…!”

SLASH! SLASH! SLASH!

I kept attacking; each slash was quickly multiplied into multiple attacks at once, constantly accumulating more and more pressure into the cracks, which were trying to constantly regenerate back to normal.

Crack, crack…

CRACK!

Until finally…

“HYAAH!”

SLAAASH!

I concentrated hundreds of slashes into a single powerful attack through the Thousand Blades Skill, piercing through the large cracks once more, finally opening them completely!

CRASH!

The empty air shattered into pieces as if it were glass, and another side opened, revealing a new set of corridors and rooms.

“It looks like this is the way out.” I smiled. “Everyone, quickly come here!”

I called my Familiars as we jumped out of the cracks and into the next Pocket Dimension, the cracks beginning to slowly recover to normal.

The Purgatory Realm goes with me wherever I move, so it doesn’t matter if I don’t bring Sara out right now. Though she seemed almost finished,.

FLUOSH!

The portal opened again, and she walked out of it feeling very refreshed and covered in a lot of dragon blood. I noticed Astaroth’s body behind, covered in countless holes and terrible wounds, which slowly started to regenerate.

I was almost feeling pity for him. Well, almost.

“Phew… That felt really good.” Sara smiled, her eyes suddenly glowing bright red. “I think I’ve understood my new powers better and who I truly am. I am rather thankful to him now, actually. If I hadn’t died back then, I wouldn’t have been able to become so strong now. I don’t know if I’m even a human anymore, but that’s fine with me too.”

“Glad you’ve adapted better to your body.” I smiled. “Now calm down for a bit; you’re all covered in blood! {Cleaning Light}”

FLASH!

I conjured a simple light spell, cleaning her entire clothes from the blood, as Sara thanked me, smiling sweetly and with her crimson eyes glancing directly towards my eyes.

“Thank you so much, Anna.” She smiled, suddenly bowing down to me. “I know what I’ve become, and it’s also thanks to your benevolence. You could have left me dead, but you decided to bring me back. I know why I feel this connection with you; you’re the one who helped me wake up from the dead, right?”

“Well, yes.” I sighed. “I used the spells imbued on Hel’s Grimoire, an item I got for defeating her,” I explained.

“I see…” She nodded, gently grabbing my hand and kissing her. “You’re strong, smart, and incredible. If you allow me, I will follow you as your loyal companion until the end of this madness in the world. This is my oath, as an Assassin, and also as an Undead raised by you.”

“Sara…” I sighed, feeling slightly guilty. “You don’t have to feel the necessity to do this, but... Fine, I doubt I can fight against your desires like this.”

“T-Thank you so much, Master!” She smiled happily.

“Anna! Call me by my name! I’m not your master; I’m your companion and friend, remember?” I smiled. “So no weird titles; that gave me cringe.”

“Fine.” She nodded. “Thank you, Anna.” She quickly stood back up and hugged me tightly, embracing me with her long arms and pushing my head into her large breasts.

“Huh?!” I cried in surprise; her chest was so puffy too!

“Ah, you’re so warm compared to my cold body.” She smiled, feeling rather blessed. “A-Ah! What am I doing?!” She quickly stepped back.

“It’s fine; it was just a hug.” I shrugged.

“But I felt this weird passion... I don’t know how to describe it. I wanted to embrace you.” She sighed, feeling strange about herself.

“I-Is that so? Maybe because you’re kind of like my Familiar…” I sighed. “B-But anyways, it doesn’t matter, really! Let’s just keep moving forward, shall we?”

“Right…” She nodded, and her embarrassment, which made her blush a lot, slowly calmed down. “Let’s go; we have a lot to do yet!”

“Indeed… There are two people a few miles from here; let’s go!” As we stepped forward, I received several System Messages.

Ding!

[Character: Sara] has managed to accept what she has become and has fully embraced her new identity and strengths, while accepting her previous death and looking forward to a new future.

[Not only has she found a new meaning to her new life, but she has also humiliated the one that took her previous life, venting all her frustrations and feeling much better about herself.]

[Character: Sara] has undergone Character Growth, learning the new Skill: [Spectral Fighting Techniques (A)]!]

[Skill Copy Conditions have been fulfilled; you can now Copy one of Sara’s Unique Skills.]

[Available Skills]: [Spectral Body (S)] [Undead Master (S)] [Phantasmal Veil (S)] [Spectral Fighting Techniques (A)]

Not only did she acquire a new Skill thanks to her [Character Growth], some sort of ability my Privilege gives to other people, but the Skill Copy Conditions were finally fulfilled!

Now, what should I take?

-----