Lala Satalin Deviluke (ララ・サタリン・デビルーク Rara satarin debirūku?) is the main female protagonist of To-Love Ru and Motto To-Love-Ru, but takes a more minor role in To-Love-Ru Darkness. The story begins with Lala running away from home as she didn't want to get married to any of her suitors. Due to an accident, she ends up naked in Rito Yuuki's bathtub. Upon arriving on Earth, Lala pretends to love Rito to keep herself from getting married, but really fell in love with him after she misinterprets a statement that Rito shouts in self-defiance.

Lala is a highly attractive teenage girl with long bubble gum pink hair, emerald green eyes, curvaceous and often referred to as a perfect girl. Her most distinguishing feature is her tail which extends down from the base of her back. Her tail is long, thin, and ends with a heart-shaped tip. Another feature is that she is almost always seen wearing a hair clip with thick black swirls circling once then pointing downward. This is her robot companion Peke who actually forms the clothes she is currently wearing. Ryoko Mikado referred to her in chapter 30 as "Devilukean" in a manner which suggested it was the name of her species. At the beginning of the series she is almost always seen in her costume robot Peke's "Dress Form", in what can only be called an enlarged version of Peke herself. Wanting to fit in more with the people of earth, she now has Peke dress her in various earth clothing styles; she has also bought herself a large number of earth clothes to wear when Peke is out of energy.

From chapters 44 to 56 of To Love-Ru Darkness Manga Series, Lala was temporary turned into a small child-like version of herself due to using too much of her power, similar to her father. On the day she returned to normal, her body gradually aged up in 2-3 year increments.

She is incredibly enthusiastic about the smallest things and has a very bubbly and slightly childish nature, which is most likely the result of being raised as the first princess of Deviluke. Although she can also be a bit of an air-head and a scatterbrain most of the time, she is known for her genius-level intellect as seen in her amazing array of inventions; her planet even wanted to use her for weapons research and engineering. She is very caring and generous and appears to have a need to make everyone she cares about happy, even those of which she doesn't have any real relationship with, such as her teacher. This trait, along with her vast intellect, is obviously one she inherited from her mother. She is very naive about earth culture and will often make highly dangerous mistakes by either accident or serious miscommunication.

Despite her naturally cheerful and somewhat childish nature, Lala is not as emotionally immature as she would appear. She has, on rare occasions, become upset and angry at other characters even Rito over serious issues. One incident in particular involved her spending the night with Haruna because Rito had yelled at her, which made her doubt if her affections would ever be reciprocated (Chapter 31). She also sometimes is known to lust over Rito. One great demonstration of her emotional maturity was when during the Trouble Quest incident, her sisters tried to force Rito to admit his feelings for her but upon seeing the stress he was under stopped them after having already found out that he does like her in some way. After this, Lala noticed that Rito was under a lot of stress due to his confession in front of Haruna. Lala later admits to Rito that she could sense that he was upset, Lala felt very upset and guilty due to the fact that it was her sisters who caused Rito's confession. After a talk with Haruna, and another talk with Lala, Rito felt better (Chapter 99).

As a child, Lala led a very mixed lifestyle, having the company of her robots, sisters and Ren/Run. However, she also underwent something of a refusal to have a real childhood. Having a mother that was almost never around, constantly having to be taught things she had no interest in against her will and being 'raised' by her father who never spent any time with her, she greatly longed for a pent-up need to express herself creatively and happily to overcome such underwhelming and even traumatic instances, which more than likely resulted in her very cheerful, very upbeat personality she never seems to let go of.

She has also shown an amazing level of compassion for other characters, beyond simply being charitable or helpful. One example of this is when Haruna admitted to her that she is also in love with Rito, Lala not only moved out of his cupboard in favour of a joint house in the roof with her sisters but also stopped throwing herself at Rito to hug him in order to be fair to Haruna and make it easier for her. Another example is when Lala and her sisters were younger and fought each other, Lala would often leave her inventions around so that they would settle their differences and work together, even though it would result in Lala getting lectured by Zastin.

On some occasions, Lala will say something ironic in relation to her own decisions. For instance, telling Saki not to run away from home, or telling Momo not to sneak into someone's bed when they are sleeping, hinting at a small piece of hypocrisy in her.

Due to never really being alone her entire life, she has no notion of modesty and is more than happy to walk around naked, but has in more recent times gotten better at knowing where and when not to be naked, though she still makes a habit of walking out of the bathroom naked when she needs something. It can be pointed out that although Lala holds no real issue with appearing naked around people, more so in recent times, she is in no way perverted or in any way interpreting the action as sexual. She actually is for one very bashful when it comes to being touched or viewed in a sexual way or from any overly compromising angle. Rito found out about this after she landed on top of him when they were on their way to save Celine and was for once incredibly embarrassed about this. However, while she has no sexual intentions, Lala seems to take some amusement from making Rito blush and panic, a sight which she has declared 'cute' more than once.

She is also incredibly optimistic. A good example of this is at the end of To Love-ru (original), Rito confesses to Lala that he loves her and that he loves Haruna too, she just says to marry both of them, being completely okay with a concubine. Later in the chapter Rito accidentally says "I love you" to almost the entire female cast she is even more ecstatic saying that he can marry everyone.

In To Love Ru: Darkness, Lala has seemed to mature slightly, though she still will walk around the house naked at times and continue her other usual tendencies. Lala and Rito seem to have a much better friendship, especially due to the fact that Rito confessed his love to her. However she also constantly tries to push Rito into confessing to Haruna as well, so the three of them may get married, Lala has even put her feelings aside until then, she no longer clings to him very often. As the series progresses Rito realized that it is bad of him to treat Lala as if she's insurance to his love with Haruna, and even starts to consider Lala's offer of marrying both of them, which he constantly shakes off.

With some encouragement from Momo, Lala starts showing her love towards Rito like she did before as her old childish clingy self, but Momo showed her some love simulation game to teach her how to express her love in a more adult way. Afterwards, she warped to him while he was taking a bath and and asked to try a kiss.

Despite her childish personality and immaturity, it has been stated by Momo and felt by Rito that Lala has an "overwhelming impish aura," with Momo wondering just how strong it would be if Lala ever found out what happens after a kiss. (To Love-Ru Darkness chapter 35)

Little Lala

As the first daughter of King Gid and Queen Sephie of Deviluke, Lala was born the first princess of the planet Deviluke. She has two known siblings, the twins Nana and Momo, whom she is very close to. As a child she was friends with the Memorze royal Run/Ren, though she seemed to prefer Run who she used to unknowingly torment. She is known to have a rather pleasant relationship with her father as she warmly recalled to Rito of a time that she was lost in the forests of Deviluke and how her father found her and took her back to the palace on his back. It was not long after then that she built Peke the costume robot which allowed her to fly and gave her a permanent friend to always be with. As the first princess and presumed eventual successor to the throne of Deviluke, it appears that she must marry so that both she and her spouse can rule together. As such she was continuously presented with male suitors, all of whom she has turned down. When she finally couldn’t take it any longer, she escaped from her home but some men chased her out of panic she warped to earth so that she could have some freedom and temporary safety.