Code Lyoko (2003)

Four young friends venture into the digital realm of Lyoko, where they confront the formidable sentient AI known as XANA. Partnering with Aelita, a virtual human with unique abilities, they engage in thrilling battles to protect both the virtual and real worlds. As they navigate the challenges posed by XANA's relentless attacks, the kids must balance their daily lives with their roles as defenders, uncovering secrets and forming deep bonds along the way. The series blends adventure, technology, and camaraderie in a captivating quest against a powerful adversary.