Devildom

The Devildom is one of the three worlds mentioned in the game. It is where demons reside and where the majority of the game takes place. The Devildom is a distinctly different realm from Hell, presumably existing in a plane just above it.

There are eight layers to the Devildom, and as mentioned during the normal story mode, the Demon King -- Lord Diavolo's father -- lies willingly dormant at the very bottom. Due to this, Lord Diavolo rules as the de facto king of the Devildom.

In the Devildom, there is no sunlight. The world exists in a constant state of darkness at all times and according to Diavolo, there are different degrees of darkness depending on the time. Despite this, demons still adhere to a "day/night" schedule where they sleep and are expected to awaken in the "morning" as evidenced by the fact that the demon brothers often sit down together for breakfast and dinner as well as go to sleep and attend school/work at specific times.

In a text from Asmodeus, its alluded that there are four seasons in the Devildom despite the lack of a true day/night cycle. From this text, it can be assumed that the seasons function the same or at least similar to the four human world seasons, although currently (up to Lesson 16) there is no canon evidence of this aside from the text from Asmodeus.

Known Locations

 * House of Lamentation - the seven demon brothers' home, MC moves in with them at the beginning of the story.
 * Royal Academy of Diavolo (RAD) - the Devildom's school, the game's characters attend it.
 * Demon Lord's Castle - Diavolo's residence.
 * Purgatory Hall - dorm for exchange students; Simeon, Luke and Solomon live here during their stay in the Devildom.
 * Hell's Kitchen - a casual restaurant with a bar visited in-game; one of the sites for Jobs. Beelzebub often eats here.
 * Hocus Pocus - a shop that specializes in magical items and such. Satan often shops here to prank Lucifer.
 * Akuzon Delivery Center - a shipping center where Leviathan often purchases his anime or gaming goods from.
 * The Fall - a popular nightclub that Asmodeus frequents and often use for celebratory occasions; one of the sites for Jobs.
 * Majolish - a clothing store that Mammon, Asmodeus, and sometimes MC will shop at that offers designer clothes.
 * The Royal Library
 * The Mausoleum
 * Ristorante Six - a fancy restaurant visited in-game; one of the sites for Jobs.
 * Cat's Eye - a restaurant mentioned in-game.
 * Goetia - a hair salon that Asmodeus goes to.
 * Headless Café
 * Madam Scream's - a popular bakery.
 * Diavolo's Private Beach - a private beach own exclusively by Diavolo where it has an artificial sun.
 * Hell's Burger
 * Hell Supermarket
 * Hell Dome - Likely a structure that holds events such as a sweets fair.

History
In Lesson 30-1, Satan and Simeon expand on Devildom history. The Devildom came into existence alongside the Celestial Realm and exists in tandem with it. Shortly after its creation, a primeval forest covered the entirety of the Devildom.

Currency
The currency used in Devildom is called Grimm which can be gold coins with a skull, or brown banknotes. The player also uses this currency for various expenses in the game; upgrading cards or unlocking spaces in the devil tree cost Grimm. Players can obtain Grimm by clearing battle stages or sending characters to work at D JOBS. Tasks and pop quiz events also often include Grimm as rewards.

Food and Drink
Eating in Devildom is a sometimes dangerous experience, as some foods are too strong, too dangerous, or otherwise inedible for MC. The rest of the Student Council looks out for MC in this regard, but there is also mention of food from the human world. It seems that there is some mixing of foods or foods inspired by the Human World.

Drinks

 * Demonus: an intoxicating drink for demons, but doesn't have an effect on MC. (Limited Item)
 * Barbato's Tea: favored by Diavolo and Lucifer likes it as well. (Surprise Guest Item)
 * Black Coffee of Melancholy (Surprise Guest Item)
 * Paradise Blue: Simeon's favorite drink, but Mammon and Leviathan likes them too. (Surprise Guest Item)
 * Little Devil Mango Slushy
 * Bufo Egg Milk Tea: Leviathan's favorite drink which happens to be popular with succubi. Similar to Bubble Tea.
 * Chaos Devil Cider: A type of cider that Mammon likes to mix with ginger ale.
 * Orange Acid: Likely a type of soda that Leviathan likes to mix with ice tea.
 * Shadow Coffee: A type of coffee Lucifer likes to mix it with bitter oolong and black tea.
 * Red Coffee: a type of coffee mentioned in Devilgram: A Cup of Red Coffee.
 * Hell Coffee: Known to become bitter when the brewer has feelings for the someone who they’re brewing for. (Seen in chat Bittersweet)
 * Hellfire Rose Tea: One of Barbatos' special tea blends.
 * Sparkling Fresh Bloody Soda

Meals

 * Family Pack Sushi: Belphegor enjoys this tray (minus wasabi), and Beelzebub likes it as well. (Surprise Guest Item) According to the text "Sushi Cravings", there are shadow hog, devil salmon, grilled vampire, bufo toad, devil zebra meat, and devil moray.
 * Spicy Rainbow Pizza: Leviathan prefers this pizza, but Satan likes it too. (Surprise Guest Item)
 * Fried Scorpion Sandwich (with vinegar and tartar sauce)
 * Red Spider Sandwich
 * Backstabbing Sandwich (Surprise Guest Item)
 * Pasta with Mixed Entrails, Sliced Anaconda, Fried Tarantula, and Nile Crocodile Brains
 * Cursed Goat Tartare Sandwich with Cheese: The Lord of Flies favorite food.
 * Burgers: 4,000-year-aged Cheeseburger, Shadow Goose Burgers, Gigadeath Burger, Poison Bleu Cheese Hamburger, Double Poison Cheeseburger
 * 500-year-old extra sticky fermented beans: One of the choices in the TSL Quiz.
 * BLT Devil Sandwich: Simeon's specialty
 * Shadow Swine Offal: one of the meals served during the castle retreat.
 * Grilled Snake
 * Quetzalcoatl Brains: Belphegor's favorite food, which can be used in various recipes like sushi for example.
 * Whole Roasted Havoc Devil
 * Vjedogonia Bile Soup: One of the dishes from Hell's Kitchen. Vjedogonia is likely a reference to "Kyuuketsu Senki Vjedogonia".
 * Shadow Goose Meat and Egg Lasagna: One of the dishes from Hell's Kitchen. Also mentioned in Cooking's So Hard.
 * Mixed Belladonna and Poison Hemlock Greens with House Dressing: One of the dishes from Hell's Kitchen.
 * Sautéed Wild Hare Liver: One of the dishes from Hell's Kitchen.
 * Stonefish Meunière with Little Devil's White Sauce: One of the dishes from Ristorante Six.
 * Purgatory-style Basilisk Boil: One of the dishes in the Reaper's cave.
 * Devildom Stir-fry with Toxic Chameleon: One of the dishes in the Reaper's cave.
 * Pot-au-feu with locally-sourced Devildom Vegetables and Flame Mushrooms: One of the dishes in the Reaper's cave.
 * Grilled Orthrus: One of the dishes in the Reaper's cave.
 * Demonkiller Remora Carpaccio: One of the dishes in the Reaper's cave.
 * Borscht with Boiled Centaur Gizzard: One of the dishes in the Reaper's cave.
 * Flaming Hot Fafnir Stew: A dish that's similar to Beef Stroganoff.
 * Roasted Roc: Similar to roasted chicken.
 * Fried Shadow Bat
 * Hellfire Curry Rice
 * Shadow Hog Ramen
 * Fried Devil Chicken
 * Hellfire Mushroom-filled Soup
 * Babylon Curry
 * Simmered Behemoth's Hind Leg
 * Creamed Bonnacon: A dish Beelzebub tried to cook this for dinner but fails for he kept eating it. He learned the recipe from the chef and owner of Ristorante Ninurta. Mentioned in the Devilgram Careful Not to Eat TOO Much.
 * Unidentified Matter: Only enjoyed by Solomon. (Surprise Guest Item)
 * Giant Shadow Sea Cucumber in Milk Stew
 * Black Tapir Roast: A dish that Barbatos made while Simeon was visiting the castle.

Fruits and Desserts

 * Princess's Poison Apple: Lucifer is fond of these, but Leviathan and Asmodeus like them too. (Surprise Guest Item)
 * RedxRed Apple Pie: Satan enjoys these. (Surprise Guest Item)
 * Wicked Cupcake: Asmodeus likes these, but Satan likes them too. (Surprise Guest Item)
 * Comfort Candy (Surprise Guest Item)
 * Shadow Chocolate-Dipped Donut
 * Madam Scream's Macarons: Barbatos' favorite treat. (Surprise Guest Item)
 * Barbatos's Signature Cake: Luke loves them, but Lucifer and Asmodeus will eat them as well. (Surprise Guest Item)
 * Spider's Web Cream Puffs: a teacake that Barbatos prepares for MC.
 * Ghost Pumpkin Cream Puffs: a Halloween-exclusive treat at Madam Scream's that Beelzebub invites MC for.
 * Pitch-Black Shortcake
 * Lunatic Pudding: a pudding with a warning that human consumption will produce pheromones that potential mates find desirable for 24 hours. Mentioned in the Devilgram Enchanted Pudding.
 * Mango-Flavored Little Devil’s Gelatin Parfait: A parfait that Asmodeus offered to MC.
 * Snow Beary: Headless Café’s exclusive item only available in the summer. It was also seen in the anime “Polarbeary Café”.
 * Hellfire Mushroom Rolled Cigar Cookies: Diavolo's favorite treat.
 * Babel Parfait: A parfait that's compared to a mountain that's available at a ghost-run café in Devil's Coast.
 * Hell Cream Cat Tongue Cookies: A confectionary from Madam Scream's, which is enjoyed by Beelzebub and Little D. No. 2.
 * Ultra Monster Parfait: The largest Parfait in the Devildom.
 * Hellfire Chocolate Pie: A dessert from a sweets Fair. Mentioned in the chat, "Sweets Fair" with Solomon.
 * Poisonous Cheesecake: A dessert from a sweets Fair, which is the most popular dessert. Mentioned in the chat, "Sweets Fair" with Solomon.

Snacks

 * Instant Noodles (Hell-Sauce Flavor): Mammon's favorite food and will try to cook this for dinner (if MC lets him). (Surprise Guest Item)
 * Spicy Newt Chips: One of Beelzebub's snacks.
 * 666 Fries
 * Popcorn: A snack from Devil's Coast that comes in flavors from Devildom, the Celestial Realm, and the human world.
 * Demon Zebra Churros

Trivia

 * It is presumed that the Devildom's time schedule exists in the same 24-hour rotation that the human world adheres to due to the fact that MC's D.D.D. is set to a 24-hour clock
 * There are several ways to get out of the Devildom as per Lesson 11-4:
 * One of several "external magic seals" that work as passages between worlds
 * All demons aside from Lord Diavolo, Barbatos, and Lucifer must receive "permission in advance" before they can use the seals due to the previous misuse of their free availability, which is strongly implied that Mammon was the reason for limiting the use of seals.
 * Considered the "classic route", an individual can walk through all eight layers of the Devildom on foot, however, it is considered "too long" and, as Lucifer mentions, would destroy MC's psyche.
 * Witches or sorcerers can also summon individuals out of the Devildom, though there are alluded consequences to this method.
 * According to Satan, books from the human world are very rare in the Devildom, especially first editions.
 * Akuzon is a play on the enterprise Amazon and "akuma", which is Japanese for "devil".
 * The moon in the Devildom is portrayed much larger than in the human world.
 * In A Special Ceremony, Lucifer mentions that New Year's is celebrated every 100 years in the Devildom.
 * In Cooking on a Rainy Day and Shelter From the Rain, it rains in the Devildom.
 * In Lord Diavolo's Fast Food Adventure, there's an AkuDonald's, which is a parody of McDonald's.