Astarotte Ygvar (アスタロッテ・ユグヴァール), more commonly known by her nickname Rotte (ロッテ) (commonly mistranslated as Lotte), is the main protagonist of the series. The title of the series, either the manga (Rotte no Omocha) or the anime (Astarotte no Omocha!) is named after her.
Rotte is a succubus and the daughter of Queen Mercelída. Naoya becomes Rotte's toy after she is forced by Judit to take a man for her harem since, like all succubus, she will eventually need to consume Sauzfryma, better known as sperm, in order to maintain her health as she matures. By coincidence, Naoya turns out to also be the father of her half-sister and friend Asuha, which she does not learn until further in the story.
Rotte is a young girl with sage eyes, long golden blonde hair, tied in pigtails which are held by red ribbons. She is mostly seen either wearing her school uniform or a blue sleeveless dress with a white high collar, purple cuffs and long knee length stockings with purple pumps.
Rotte is the first princess of Ygvarland, a fantasy kingdom with appearances very similar to medieval times only magic exists all around. Rotte, as her close friends call her, is a ten year-old succubus and is at the age of needing to build a 'harem' as her mother (Mercelída Ygvar) once had to.
As a succubus Rotte needs male's "life-seed" to keep her life-force and magic in check, not doing this will lead her to to become powerless and perhaps perish. An incident occurs when she was younger: she encountered a male entering her mother's bedroom at night, which frightened and confused her. In the manga, it's stated that this actually happened when Rotte was already sleeping with her mother in bed. After that night, Rotte has despised males and has always avoided them, endangering her future due to her succubus nature.
Rotte lives in a huge castle with waiters, servants and maids who tend to her needs. The head of the staff, Judit, fully understands how succubi live and what they need to keep on living, but, to her dismay, Rotte hates males which always led the two to argue over it. Finally, after Rotte's 10th birthday, they came to an agreement that she will only have a 'human' male as her first candidate for her harem. However, in the world where they live, humans are very rare and only appear at a certain time through a magical tree, Yggdrasil which connects to the human world. The tree had since long lost its magical power, which is the reason why Rotte puts that condition to accept a male, thinking that Judit will be unable to get a human. But it turns out that Judit is able to use Yggdrasil and procures a human boy named Naoya Tohara, who decides to leave his world and bring his daughter Asuha to live with him and the princess.
Rotte has always been much of a loner. She doesn't talk to any of her classmates at school because she thinks they will treat her differently because they know she's a princess. She only relies on few people from her manor: Judit, Olav, Zelda, Effie and Cú. Other than them Rotte doesn't talk or interact with anyone. Lotte was once close to her mother, always by her side and wanted nothing but love and attention from her, but, because of her mother's flirty personality which drew many males eyes, she felt pushed out and was scared of all the males she kept encountering.
Rotte's personality varies depending who she's with. She's mostly stubborn and childish, but can be very quiet if she's in a crowded area such as school. Rotte, at first, wants nothing to do with Naoya and Asuha, With Naoya's patience, kindness and caring attitude and Asuha's playfulness, after a few days of living together with them, Rotte slowly opened up, revealing a talkative, willing and playful personality. With Asuha's help, she made friends at school and also began seeing her mother again.
After getting used to having good company and Naoya's care, she began to harbor small feelings for Naoya, which grew the more time they spent together. She turns more tsundere towards him, but also wants him to be around her and only her, getting jealous if his attention is elsewhere or with someone else.