Deviluke

Deviluke is referred to as being the center of the galaxy, though this is probably a reference to its importance rather than its placement in the universe. The planet of Deviluke literally rules the galaxy after the galactic unification wars led by King Gid Lucione Deviluke and as such, they hold dominion over all of the planets of the galaxy and its people.

Little is known about the planet itself other than its rather Gothic image,  its containing many forests, really high mountains and its high level of technology. Much more is known about the citizens of Deviluke who are, at least, known to be many times stronger than Earthlings, and seem to have won their wars over the galaxy using just their own natural powers, which seem to have some sort of variety.

Appearance
Like their planet, the appearances of the Devilukeans follow a theme of devils and demons. All Devilukeans have tails at least half as long as their body length that ends in a shape particular to them or their possition at its end. The Devilukean princesses' tails all end with a spade shape; the Devilukean king, Gid, has a tail that ends like a trident; the palace guard commander, Zastin, has a tail like a scorpion; the royal palace guards have diamond-shaped tail end. No other examples have been seen.

Their clothing follow the devil theme as well, but also appear to be inspired by playing cards. Emperor Gid's true form wears a black outfit that could be described as resembling a Gothic dark prince. Zastin is almost always seen wearing an archaic stone-like gray armor with many sharp edges, which might have appeared rather sinister were it not for its presence in a light-hearted manga series, and Zastin's own comically inept character. The princesses often wear black devil wings on their backs, which enable them to fly. Their clothing seem to be inspired by playing cards, mildly modeled after harlequin outfits with light frills, has a slight diamond motif, and striped stockings.

Lala's iconic "Peke" outfit is unique to herself. Besides the black wings, it does not seem to follow any kind of Devilukean trend, but rather is simply designed by Lala's goofy imagination, which is dominantly white, round and curvy, much like most of her other inventions.

Royal Family

 * King of Deviluke - Gid Lucione Deviluke
 * Queen of Deviluke - Sephie Michaela Deviluke
 * Princesses of Deviluke
 * First Princess - Lala Satalin Deviluke
 * Second Princess - Nana Astar Deviluke
 * Third Princess - Momo Velia Deviluke
 * Royal Palace Guards
 * Commander - Zastin
 * Assistants - Maul and Smutts

Powers and Abilities
All Devilukeans have superhuman strength. They are much stronger than Earthlings and most aliens of the galaxy. At one time, Lala even reached a stalemate against Yami, a well-known assassin, with just using her brute strength. However, Yami admits that living peacefully on Earth has weakened her. Another display of the Devilukeans' strength is when Gid was able to hit a tennis ball so hard that it caused Sasuga, the tennis club's adviser, to faint while standing.

Some Devilukeans have sort of blood lust emotion through fighting or when simply tempted by someone who gets them mad. Others like Momo have a lustful desire for sexual pleasure.

Devilukeans are also able to shoot beams from the tips of their tails, and when used in tandum with one another, it creates an even more powerful blast. However, so far, only Lala, Nana and Momo have used this power (laser beam for Lala, and lightning for Momo and Nana), so it is unknown whether this ability is exclusive to the Devilukean princesses, or to Devilukean females, or if all Devilukeans can do this. It's possible that all Devilueans have abilities that's unique to them, such as Nana is capable of talking to animals and Momo is capable of talking to plants.

Weaknesses
Despite the Devilukeans' "perfect warrior" abilities, they still have weaknesses. The overuse of thier power can cause them to revert into their child-like forms, such as the case with Gid's current form and Lala during her fight against Yami in Darkness Chapter 44, although in her case it's temporary.

Some Devilukeans are shown to have sensitive tails. When someone touches it, the Devilukean will lose power, but might manage to find enough strength to throw said person and let their tail go. The feeling of having thier tail touched gives them an "erotic" sensation. However, this weakness is only shown between Lala and her sisters. It's also possible that this weakness is only limited to a certain few, as when Nana was asked if this applied to everyone, she mentions that everyone's different (Motto To Love-Ru Episode 11). As seen with Momo, Devilukeans with sensitive tails can pleasure themselves by rubbing it.

Trivia

 * In the anime, the way Devilukeans propose is by grabbing the females' breasts and perhaps confess to her. Coincidentally Rito accidently did both without knowing it. Within the three days after the "said event", there is a cooling off period to cancel the engagement by touching the female's breast again.
 * The second names of the Devilukean Royal Family are reference to demons.
 * Gid "Lucione" Deviluke - Lucione comes from Lucifer.
 * Lala "Satalin" Deviluke - Satalin comes from Satan.
 * Nana "Astar" Deviluke - Astar comes from Astaroth
 * Momo "Belia" Deviluke - Belia comes from Belial.
 * There have been several information about Deviluke and the Devilukeans that resembles Planet Vegeta and the Saiyans from Dragon Ball. Whether these resemblances are intentional or coincidental are unknown.
 * The Devilukeans have superstrength, much like the Saiyans.
 * Devilukean women grow weak when their tails are touched, like the Saiyans.
 * The Devilukean king, Gid, was originally regular sized, but became small later on. The same thing happened to Goku in Dragon Ball GT. However, the reason why they became small is different.
 * In the first chapter of the manga (and the first episode of the anime), when Lala was showing Rito her tail, she commented "Even though I have a tail, that doesn't mean I transform when I see a full moon". This was an intentional reference to Dragon Ball, since Saiyans transform when they see full moons because of their tails.
 * Both planets conquered other planets. However, in the case of Planet Deviluke, the Devilukeans conquered planets in order to unite them during the galactic unification wars, while the Saiyans conquered other planets for bounty.
 * Both planets are notorious across the galaxy, and the other aliens are afraid of them.