Sasaeng was a project developed in collaboration with one other designer, completed in just one week from start to finish. Despite the tight deadline, we carried out a full design process—from in-depth research and user analysis to building a complete UI kit and delivering a high-fidelity prototype. The concept behind Sasaeng is both playful and thought-provoking. The app is designed to help users track and improve their personal progress through a unique mechanic: a digital pet that follows you everywhere, almost like an obsessive fan—hence the name Sasaeng. This “companion” monitors screen time, encourages healthier habits, and supports personal goals. To make the experience more holistic, the app also integrates features such as guided meditation courses, goal-setting tools, and customizable reminders. Users can tailor Sasaeng to their specific needs, whether that means reducing distractions, improving focus, or finding moments of calm during their day. The challenge was to design an interface that balanced the slightly ironic, playful personality of the pet with the seriousness of self-improvement. Through a clean, modern UI and carefully chosen interactions, we ensured that the app feels engaging without losing credibility as a tool for personal growth. Sasaeng demonstrates how design can merge humor, accountability, and wellness into one cohesive experience. It reflects not only the speed and efficiency of our design process but also our ability to create a meaningful and memorable product under time constraints.