Debut 21 is a futuristic spinoff/spiritual successor to Tanjō: Debut. The player is tasked with raising an idol as they become popular and managing their stats, but the twist here is that the game is set in 2020 , and the idol you are tasked with managing is an android, named Ai Kanzaki.
The player's goal is to guide Ai Kanzaki through an entire in-game year, raising her stats and keeping her stress level within reasonable limits. The game features real-time 3D graphics, a departure from its 2D predecessor.