A mature and sensible archaeology major who lives in the student dorm at the university. She is a year older than her classmates. While Lilli stands at the head of her class, she looks at the people around her and wishes there was more to her life than just being serious all the time. — Directory, Sonic Unleashed
At some point prior to Sonic Unleashed, Lilli attended Spagonia University, where she took archaeology as her major. Over time, Lilli came to stand at the head of her class, due to her incredible dedication. While Lilli took her studies very seriously however, she felt unsatisfied. Having only her studies to think about, Lilli longed for what the rest of her classmates seem to have, instead constantly being serious about her studies.
Following the Earth shattering, due to the awakening of Dark Gaia, and Professor Pickle's kidnapping, Lilli's classes were canceled and she was forced on an indefinite break until further notice. This made Lilli disappointed, as it meant her studies were stalling. She was unaware, however, about Professor Pickle being kidnapped.
Sometime later, when Sonic the Hedgehog and Chip came to Spagonia to find Professor Pickle. Lilli met the duo who was looking for Spagonia University and was asked if it was the building behind her, but she explained to them that it was the university dormitory, and lead them to the university. Lilli later saw Sonic and Chip come by in a rush, and she asked them why they were in such a hurry, where she was surprised to hear from them that Professor Pickle was in trouble. Lilli also told them about how annoying it was that her studies were stalling. After Sonic, Tails and Chip saved Professor Pickle, Lilli Sonic and Chip how surprised she was to hear that they saved the professor. When she also heard that Sonic and Chip were looking for one of the Gaia Temples, Lilli helped them by giving a hint to a temple's location in Mazuri.
With nothing else to do, Lilli began to socialize with the other students and came across Raimondo. The two of them began to talk together, where Lilli told Raimondo things like how Otto knew everything about his students and the funny story about how Otto had brought Lilli's grandparents together. Lilli eventually came to have a great time with Raimondo and soon began to develop feelings for him.
As Lilli believed that she had finally found something else in her life besides her studies, she was conversing with David and learned to her shock to him that Raimondo was going with Federica on a trip to Apotos, but then quickly tried to cover up her outburst. These news let Lilli to believe that Raimondo was in love with Federica. Distraught, Lilli entered a long period of sadness, and when she talked to Sonic and Chip about Federica and Raimondo, she told them about how close she thought them to be.
When Raimondo and Federica returned to Spagonia, Lilli remained in the shadows, not daring to confront Raimondo about her feelings for him, because of Federica's own feelings for Raimondo. Instead, Lilli went to Raimondo's friend, Franco, and asked him if Raimondo was going out with Federica, but Franco was not sure what to say about it. Lilli, however, was aware that Federica had a crush on Rainmondo and asked Franco to tell the truth. Lilli was then informed by Franco that while Federica liked Raimondo, it did not seem that Raimondo was thinking about Federica as his girlfriend, which gave Lilli a small glimmer of hope.
Not long after, Lilli met Federica, who openly admitted that Raimondo only thought of herself as his friend. Lilli was, however, both shocked and confused to hear this and told Federica that since they went to Apotos together, she believed them to be a couple. This let to Federica asking Lilli if she was holding back because of her, to which Lilli hesitantly admitted. Federica then told Lilli not to worry about her and encouraged her to go after Raimondo herself, leaving Lilli vocally stumped.
With new-found courage, Lilli found herself talking to Raimondo again, who told her that Franco had told him that she liked him, before admitting that he had thought about her a lot lately, which made Lilli ask Raimondo in disbelief if he meant it. Lilli was then again surprised when Raimondo asked her if she wanted go on a trip with him, where she timidly replied that she would like to and that she would like to go to Shamar with him. Now in a serious relationship, Lilli heard how Raimondo wanted to always be with her, and Lilli replied that she felt the same way and that she was the happiest she had ever been.
Lilli is a smart, mature, sensible and studious girl and is usually very serious all the time. She wishes, however, for more in her life than being serious.