[Lucidrago]

Originally Posted by Le Fay

Spoiler for Calamity/Karma:

Calamity/Karma
It was a discussion that took place after Nakiri Nakagami no Oryuu ended his contest with Ikuse Tobio, left [Inner Sanctuary] and went to a certain suburban city.
It was conducted in a room of office building’s basement.
The one Nakiri Nakagami no Oryuu had a clandestine meeting with---was a man with masculine looks and brown hair. His silver eyes shone charmingly even amidst the darkness inside the room.
He was dressed in a peculiar combat uniform. It had a resemblance with the one fallen angels’ leaders wore during battle. Rather, it was exactly that uniform.
Nakagami no Oryuu accepted the discussion with this man---a betrayer from Grigori, Satanael.
Inside the modest room was nothing but a table and a chair, Oryuu and Satanael were also the only ones present.
Satanael silently turned towards Oryuu and placed official papers---a document on the table.
Looking at the document presented, Oryuu squinted and made a stern face. A serious expression he hadn’t even shown to his colleagues, fellow Four Sacred Beasts.
The man hailed as matchless [Nakiri Oryuu] was making a face unusual for himself.
He glared at Satanael and enquired of him.
“The one with black wings, is it really true? If I accept your proposal---“
Interrupting him, Satanael asserted.
“But of course. I’ll suppress the unusual power nesting inside your little sister-kun---the Sacred Gear.”
Satanael was showing Oryuu research data about Sacred Gears.
And this document---was related to [Longinus].
Oryuu rested a hand on his forehead and sighed.
“….If it had been an ordinary Sacred Gear, it still would've been better. However…”
Satanael shrugged his shoulders.
“The thing that dwells within your little sister-kun….within Nakiri Momiji…that Sacred Gear is considered the manifestation of Outer Path---of unlucky number itself. It is extremely dangerous. The chief of Five Great Houses should know how dangerous it is.”
Keeping a gloomy look on his face Oryuu made a long, deep sigh and then cut to the chase.
“…What do you want of me? What should I do to save my little sister?”
Pulling those words from the young head of the House of Nakiri, the first among Five Great Houses, Satanael answered while smiling thinly.
“I plan to conduct two big experiments in this country. All that I need is a bit of assistance. What’s with that face, the [Nakiri] house will be able to continue it’s existence even after this. So I want two things. One of them is [Walpurgis Night] by the witches of [Oz]. As for the other one---“
Satanael took out a new document and showed it to Oryuu.
“I haven’t told about this plan even to [Oz]. So I’d like you to keep it a secret. And this plan is precisely the one and only thing that is able to save your little sister-kun. ---This is also similar to innovation.”
He, Satanael, genuinely acted only for the sake of satisfying his own craving for research.
Possibilities of Sacred Gears----Sacred Treasures, elucidating on Longinus…all of this for the sake of creating [The incarnation that destroys even Gods] with his own hands.
With a childish curiosity and spirit of enquiry, he wanted to know about God’s principles.
Yes, innocently so---

So my guess is that the second plan of his has to do with the game 'Denpachi.'