In the Teri Terio Manga
Sucy was born on Manba Island in Southeast Asia as the eldest daughter of the Manbavaran family. Like most of her family members, Sucy developed a great passion for collecting poisons. Eventually she was sent to Luna Nova Academy to learn magic, although in reality, she only wanted to go to get Cockatrice poison.
In the Keisuke Satō Manga
While most of her background origins are unknown, at some point Sucy came across Ramzan Manbavaran and became adopted. One day on her birthday, she asked Ramzan about the purpose of birthdays which Ramzan told her it was about the feeling of those who were glad that it existed. At some point, Sucy left Ramzan to attend Luna Nova's opening ceremony to become a student.
Sucy is Akko's friend and uses her as a test subject for her various potions. She mocks Akko for liking Shiny Chariot, labeling the performer a fraud. Later, she joins Akko's group into the school's dungeons and kills a minotaur with a deadly potion. She later fights against the released ancient dragon alongside Akko and Lotte.
Sucy and Akko create a giant mushroom monster with their combined potion ingredients, which causes them to be punished with preparing the school's annual parade. After Akko and Lotte rip a treasured music sheet belonging to Lotte's ancestors, Sucy attempts to make Akko realize how much she hurt Lotte. She is seen keeping Lotte company and later saves Akko from falling mid-air, quickly mending their friendship. Casting Shiny Ballista, all three pacify the Titan and celebrate together.
While Sucy was heading to Luna Nova Magical Academy for the entrance ceremony as a new student, she collides with Akko who is heading to the same place. While Akko tries to talk to her, Sucy does not show any interest, using a potion to bring her stuffed animal to life, then stinging her eye and then transforming a string into snakes to get rid of her.
While flying in the ley line, reading about the Arcturus Forest, Akko collides with her once again after falling from Lotte's broom, causing all three to fall from the Leyline in the Arcturus Forest. After escaping from a Mandrake, Sucy creates a rope wheel around Akko and Lotte and causes Akko to attract a Cockatrice to get his longed for venom. After catching one of their feathers, the three try to flee in Sucy's broom, but are shot down by the Cocketrice. When Akko manages to use the Shiny Rod to take them to Luna Nova, Sucy, Lotte and Akko become roommates.
When the students are taking lotteries, Akko picked one where she and her team were to be eaten by Vajarois. While Akko and Lotte were horrified to be eaten and be humiliated, Sucy takes actual pleasure in getting eaten. While Akko complains about how this role would affect her chances in getting the title of Moonlit Witch, Sucy and the others countered to Akko that Diana was going to win anyway and Akko's lack of skills was whats stopping her from getting the title. Angered, Akko left leaving the others to continue their parts.
Akko and her roommates read up on Vajarois' backstory. Akko intends to cheer up the ghost by making her laugh and wants the support from her friends but Sucy and Lotte refused since they saw no point in helping the ghost and that it has been a tradition for a very long time. While they sleep, Akko claims she'll find a way make them see her vision.
The next day, Sucy and Lotte eavesdropped on the conversation between Akko and Diana's roommates, who were pranked when Akko was in the guise of Diana. Akko was angered that Hannah and Barbara insulted her friends while outside, Lotte lowered her head in shame while Sucy cracked her neck in quiet fury after hearing the conversation.
Back at their room, Lotte wonders why Akko kept on doing what she does with Sucy pointing out how much of a stubborn fool she is. Although, Lotte admires that part of her. Only when they saw the full plans of Akko that they started to join in much to Akko's happiness.
While Akko continues to practice her transformation spell, the two waited for their friend to arrive. Diana arrived and saw Akko no where in sight, believed she abandoned them with Hannah and Barbara insulting the young Witch further which proves to be a total mistake as Lotte finally stands up for Akko. Lotte angrily shut them down while defending Akko that she has been working hard for the past weeks leaving Diana, her group and Sucy in shock about Lotte's change of character.
After Diana finished her show, Lotte at least complimented Diana but Sucy just mentioned Diana's 'lineage' as the answer. To their relief, Akko arrived and they both head out for the sacrifice.
When the sacrifice starts, everything went insane. While Akko used her transformations to avoid Vajarois, Lotte and Sucy act as support with Sucy creating a forest of mushrooms to confuse the ghost and together with Lotte turned Vajarois' hair silly. The audience and the alumna were having a great time but Vajarois remains distraught leading to the latter to attacked the trio. Before about to be eaten, Ursula informs them of the Seed of Sorrow, which is the main reason why the ghost was in pain for centuries.
Entering, they found the seed. Akko activates the Shiny Rod into its third form. Grappling the seed, the three pulled it out and ending Vajarois' misery once and for all. After Vajarois thanks them for their kind acts, the audience roared in cheers at the amazing feat they just did.