A note from the Author: This is a compilation of my handwritten diaries, organized into a book. Enjoy.

"As for Gaius, he has no more chance of becoming emperor than of riding a horse dry-shod across the Gulf of Baiae." ― Suetonius

Vassago Residence, Principality of Vassago. November 28th, 2017.

Dear Diary,

Tonight, Maria came to my bed.

That left me almost astonished, if not for the fact my mind seems to be much clearer sthan ever before I would have surely be unable to do a thing. At this very moment, as I write under the feeble light of a spell, she sleeps calmly under the soft blankets of the enormous bed the Lord Vassago had proportioned me with.

I need not to tell we have just engaged in intercourse: aka, we had sex. Usually, I would not be even fazed by that- having been through college life, that was quite normal to me-but there is the 'Diodora Factor' that takes it to a whole other level: Our memories are one, I know how he ravished each of the members of the Peerage in an animalistic lust. This is madness.

From what I know, she came to me in free will. Maybe she is used to it, having been with my body's former owner since childhood? I have not any idea, even with a mind as sharp as mine. That aside, the love I made to her was soft and gentle, despite my own preferences. I won't go further in the description- unless you so desire, diary, though you can't express it- but I will add the queer detail that I'm used to rougher experiences.

Turning the focus from my beautiful Queen, I can humbly say that those days' events were, indeed, quite interesting.

Not beating around the bush, to say I have managed to fool Diodora's parents, Lord and Lady Astaroth, is far from an adequate description to the manipulation that happened in my new home- Diodora's estate- 3 days ago. While I prefer not to reveal their names right now, for their respective meanings are far too ironic and I believe will add some interesting detail later on, I can say the entire 'strange dreams' cover story pretty much justified the drastic change in their 'beloved son's' attitudes.

They were, surprisingly, extremely proud to see the way their hopeless heir suddenly changed into a man who planned to chase after goals, while approving the end of my 'escapades'. Yet another detail about Diodora's personal life that was not explored in the novels, the fact his parents actually KNEW what he did to his Peerage. I would have been disgusted by their not meddling on his affairs but…the body isn't mine, the world isn't mine and I'm not the one who did all those immoral acts so I can't force myself to actually care.

That leads to my current situation: as you already know, dear friend, I am currently in a visit to the insular territory belonging to the House of Vassago, longtime allies of the Astaroth clan. The ring of islands that forms the Principality of Vassago reminds me of a tropical paradise, with crystalline water and palm trees- with the only difference from my own world's tropical paradises being the lack of a scorching sun.

Officially, my 'parents' have decided to bring me on a business trip with our allies: some makeup story about exploring oil in the lake that contained the principality. However, their true intention was another one, to get me closer to the heiress and elective head of the Vassago Clan, Eneely Vassago. Quite a bold move of theirs indeed.

From reading the novels, I had the knowledge the Vassago and Astaroth were close families. So close, in fact, that their heiress declared her open hatred towards Rias Gremory and her- let me say it in vulgar terms- 'boyband' (which I ironically named Al Qaedirection) when the Astaroth lost much of their influence and prestige. However, to think my 'parents'- don't blame me for being sarcastic when using such term- wanted both clans to be this close was something unexpected.

My thesis is that all of this is related to financial matters.

To put it in simple terms, the Astaroth revenue is mostly based on the infinitely vast oil reserves found in the Dukedom's subsoil. About 70% of the House's enormous wealth is based on oil and gas exports to the rest of the Underworld, with 20% more coming from mining and agriculture and the last 10% coming from advanced technology industry and services. From what I could read in the reports on my laptop's database and from my own memories, it seems the House of Vassago allows the Astaroth Oil to explore petroleum in their 'sea'- which is twice as big as big as the Caspian sea itself- for a part of the revenue.

That explains why Diodora is so obscenely rich- as expressed in his own garments and fancy residence- while providing a reason for both clans' close relationship. It is something to take into account when I make my moves with Khaos Brigade, aka Shalba Beelzebub and Ophis, for I have no desire to lose that mountain of cash that are the oil revenues.

Those are my introductive thoughts for today. Without further ado, I shall head to the reports of how I came to be in the Vassago Principality.

_{Morning}_

This morning, I have finally confirmed how comfortable it is to be a Devil playboy with unlimited money and a harem of former holy-maiden guards- who also managed to be my Peerage. Why do I state so?

Well, my arrival to the Principality was, in essence, a show. And quite a show, dare I say. From the beaches of Vassago City, one of the five major urban centers of the Princely House's insular domain, what the Common Devil populace saw was a young, handsome Devil playboy, arriving at the port in the fanciest yacht even I- who had lived in Kuwait for some good three years- have ever seen.

SS. Astaroth was built to impress. It's a gigantic white ship, with 1,186 ft length and 215 ft Beam, decorated with the fanciest furniture and with heated pools in all of its decks. To add more fuel to the fire, I've decided to reward my Peerage with the finest food money could buy in the Underworld- with chefs from the cosmopolitan center of Agreas, in the Agares territory- and a small party on the deck.

Don't get me wrong, Diary. Despite having 'changed' my ways into a direction way from late Diodora's, the image of a playboy is something I need to- and, to be frank, would rather- maintain to avoid having my mask taken. Me being a show off aside, let me add another brief, yet more detailed, description of the Vassago territory. I have a feeling the one I added earlier on is yet not enough to be satisfactory.

Repeating what I mentioned earlier, the Principality has the almost the entirety of its land in a ring- literally, a ring- of 7 tropical islands located in the middle of an immense salt lake, which is called Sea of Vassago for practical reasons, in the centre of the Astaroth territory. The main isles are named after the Seven Deadly Sins- Wrath (capital), Pride, Gluttony, Lust, Sloth, Envy and Greed- and their climate is mostly a tropical one, with Gluttony bordering the characteristics of an equatorial rain forest.

Each of the main islands contains a major city, which are centers with about 5 million inhabitants each, as well as some minor villages. The main isles are vary in size, reaching from the size of Hawaiʻi Island to the very Kyushu island- while the minor ones are much smaller, and sparsely populated. The economy of the archipelago is mostly based on technology, with emphasis on the chemical industry due to the location in the heart of the bountiful Astaroth Duchy.

Exploring the Sea of Vassago and the islands was the main reason why I chose to come here by ship, instead of outright using a Teleportation Magic Circle to go straight to the Palace. Secondary reasons also include my own insecurities about said magic, one I have barely had the time to practice before Lord and Lady Astaroth came to fetch me at the manor, and my desire to show them their 'little baby boy' was still as flamboyant as always.

Returning the focus to the scene itself, as the yacht docked at the port of Vassago City- it seems the House's surname is quite a popular name for things at this territory- my eyes landed on the figure of the Devil sent to receive us. It was the Prince's butler, an old green-eyed, bald Devil who wore a classical Victorian suit.

Restraining myself not to snicker at such cliché garments, it seemed like every butler/maid in fictional realms had to dress like a Victorian servant, I walked down the ship's staircase into the rocky modern docks with my Peerage by my side like an honor guard. It was all part of the show, so I had to act the part.

"Lord Diodora." The old man greeted respectfully, bowing in a polite angle. While I clearly do not enjoy the idea of having servants treating me like I was a flawless master, I had to force a smile in order to brush off any suspicions. "Welcome to Vassago City, I am humbly at your service, sire."

"Very well." I replied, not bothering to ask the old man's name. From what I could observe from canon, most of the pureblooded High-class Devils- with the obvious exception being the Gremory Clan- treat the ones bellow them like trash, especially Reincarnated Devils. I hate the idea, but there's unfortunately not a thing I can do about this for the moment. "Take me to the Palace, then, servant. Me and my girls are tired of such a lengthy trip around the islands."

I'm putting a clear emphasis on my choice of words: my girls, instead of my servants. While it was nothing but a petty detail, the affectionate and, at the same time, a bit possessive meaning behind the word made my entire Peerage shiver in delight- Maria being the one who was pleased the most. That indicates some progress towards genuine affection, which is quite a rewarding fact.

And any progress is great, given my current situation as a foreigner in a universe of magic and surreal. Like the greatest pieces of Salvador Dali, DxD challenges the mind of one raised on the 'real world', aka, my plane of existence's Earth.

With that, it was in the blink of an eye that a Magic Circle with the Crest of Vassago appeared under our peculiar group.

And with that, was I welcomed to the Vassago Estate. Let the game begin.

_{Timeskip}_

It was early in the Afternoon, not the best term considering the way the 'days' in the Underworld work, when Eneely Vassago came to meet me in their gardens.

Unlucky was I, indeed, for I've spent the whole morning trying to avoid what seemed to be a troublesome heiress. Whether it was by spending time sparring with my Peerage or by practicing Magic with Maria, I've managed to keep her at distance with my girls' presence. However, it would be arrogant to presume I, as heir presumptive to the Astaroth Clan, could escape her for too long. After all, that was one of my 'parents' ' objective with this entire event.

"We're finally alone, Diodora-sama." I could hear her soft voice from behind me. Keeping my eyes closed as if in deep musings, I was actually trying to remember how the novels described her. After all, dear Diary, it would be quite easier from a reader from my own world- a foolish hope of mine, I know- if I followed what the creator of this entire world desired. Finding none, I will attempt to describe Eneely's looks with my humble words.

As I am an ignorant in what many call 'Akiba Culture', aka, anime, it is unfortunate to state that I can not refer to any other character from this type of literature. However, from my previous experiences with my World's own history, I may state that she reminds me quite a lot of 'Sisi', who most of the people know as Empress Elizabeth of Austria, wife of old Franz Joseph I of Austria.

If you wonder how I know about such figure, dear diary, it has something to do about having some drinks with a teacher from Law School. She told me quite a lot after some shots. Oh, Texas, how I miss it.

Back to Eneely. She was, in simple terms, an 'anime' younger version of Sisi, with more accentuate traits, a hair died in quite the peculiar shade of purple and greenish blue eyes that remind me of Rias Gremory's. Like every other girl in those series, she was pretty beyond possible in my original world, possibly an effect of this world being…a Japanese anime.

Yet another bizarre detail I've forgotten to add. This world is weird, totally different from my own. I'm used to a tridimensional body, made of real flesh and bones- the body of a normal human, such as Donald Trump or the hypothetical reader that might read you, should I find a way to send you back to my world, dear diary. After being turned into Diodora, however, I've been sent to a world that merged bi and tridimensional images and the typical Japanese drawings, with colors of course, which means I'm basically de facto living inside some sort of anime.

The so called weeaboos- and, yes, I'm referring to my colleague Hideki- probably dream with this, being sent into one of their beloved anime after death. They don't have a clue on how strange it is.

Yet again, will I head back to the scene.

"Eneely, you have no idea how I wanted to see you…" I finally replied, turning to face the girl who was genuinely in love with the maniac called Diodora Astaroth, and therefore in love with me. Unbelievable, yet another absurd not mentioned in the novels I've read. "I missed you, my little Rockrose."

And yes, her nickname was based on the flower. Probably because of the color of her long hair.

"I thought you…" she started, barely mustering the courage to look into my hazel eyes. Diary, this is the true face of a girl whose hatred towards the Gremory Peerage is well known in the later novels. What in the world… "I thought you've…found another woman…"

"What are you talking about?" I answered in a serene tone, reaching my hand out to caress her behind the delicate ears. Her skin was smooth, probably kept this silky with expensive products sold by the Phenex- which I've discovered to be, by the way- the owners of what I dare call Hell's Loreal. She smelled good, her perfume more pleasing than even my girls'. "My Rockrose holds a special place in my heart."

Forgive me for the words, dear Diary, but, as a proper Republican says, fuck you, Diodora, fuck you. By reading his memories, have I seen how he weaved a web of seduction around the Vassago heiress- most probably planning to turn her into his doll soon. I'm repeating, I have no idea how this happened. Sincerely, I don't even want to know.

"Oh, Diodora…"

What a cliché, sincerely, this scene made me feel like this world's version of…Mr. Darcy. Indeed, most of the Underworld seemed to prefer Victorian style so that would be a fitting character.

Sorry, it seems Maria is about to wake up, I'll have to cut my description of such lengthy and terribly romantic scene short. In brief words, I've spent the entirety of my early afternoon- which would sum up about three or four hours- with the heiress of Vassago. Obviously I avoided talking too much about certain issues- such as my Peerage, for clear reasons- and simply used the data Diodora's memories so generously provided me for the conversation, at the cost of a terrible headache, of course.

Now then, I believe it's time for the classical monologue in which I reveal some of my plans and strategies for the future. I believe you are more than used to it at this point, mon ami.

Those have been days of immense growth by both my girls and myself. With my Prussian training regime and focus on their strengths- while not forgetting to make their weaknesses adequate at least- giving off the expected results.

Should they follow this pattern, I believe we'll be more than ready for the Gremory group- at the level they were during Diodora's betrayal, of course- in two or three weeks. Seekvaira is a given, Diodora was able to defeat her using Ophis' Snake, so I- with a keen mind and the harsh training- will be more than capable of defeating her without cheating. Cleria is a wildcard, she did not appear on canon, nor did her Peerage. She is the biggest of my worries at the moment, with the others being reserved for the close future.

Have I mentioned how easy this world really is to manipulate? Analyzing the plot, one keen individual may easily notice how absurdly fast both Issei and Rias- excluding some other characters such as Akeno for practical reasons- grew into juggernaughts that could crush lots of immensely powerful opponents. Without any super harsh training, that is. I truly wonder how far an individual can go when submitted to the tests I've been performing on myself and the girls.

Asia is the most important of my later goals. From what I can deduct, she is still living somewhere in Italy, so there is still some time before she comes into the scene as the weak, kind healer who later reveals herself to be quite the unstoppable beast. My plan is simple: impede Issei from saving her, save her myself and make her Rias' bishop- for my current body's previous owner already had a full set before my reincarnation as him. Why? Well, I confess my motives are none but the simple desire for what people refer to as 'roleplay'. I am Diodora now , so following with his plan- in a lighter version where there is no mental breakdown of a nun- is not half as bad as letting Issei snatch her for his petty harem.

Thinking about the Red Dragon Emperor, I've gotten an insight right now. I'll not write about it for the moment, so that I can muster the ideas and organize the plans properly. Let me tell you, however, that it is quite interesting.

And yet again, am I interrupted. Seriously, it's been quite difficult those days to write…it seems like there's always someone looking for me to talk or train or spar. Maria's awake now, I'll come back to you after the Rating Game with Cleria.

My time with you is annoyingly short, I'm anxious for some proper time with you, my friend. See you at Japan, and don't forget to wish me luck.

Sincerely, me. Good night, dear diary.

Fin.