Null, a young genius, rebuilds her deceased older sister as a robot named Peta after a tragic accident. The robotic Peta exhibits distinct behaviors, creating comedic and challenging situations within their sisterly bond. Null constantly manages Peta's malfunctions—ranging from detached plugs to unexpected aggression, sometimes involving tools. Beyond maintenance, Null supports Peta in combating threats like the Queen Bug in cyberspace, where Peta utilizes specialized debugging weaponry. Reluctantly attending school and consuming disliked nutritious food, Null demonstrates growing responsibility. Her initial motivation evolves into a protective commitment to their partnership, tested during shared experiences including a space trip. An original video animation episode explores their post-reconstruction interactions. This mechanical rebuilding fundamentally alters their sisterhood, forcing Null to navigate Peta's altered personality and capabilities while confronting the complex emotional and practical consequences of her creation.