Lockdown Zone: Lv. X

On Christmas Eve, high school student Ryouka Tsurumi finds herself in an unusual situation when her family's mansion is suddenly placed under lockdown. Her mother informs her that the area has been evacuated due to the presence of a mysterious and dangerous entity known only as X. With most people gone, Ryouka discovers she's not entirely alone - her childhood friend Shuuhei Murosaka remains in the building with her. As Ryouka and Shuuhei navigate the increasingly perilous situation within the locked-down mansion, they must work together to understand the nature of the threat they face. The entity X appears to possess terrifying abilities that make escape seem impossible, and the two friends find themselves caught in circumstances beyond their understanding. What begins as a desperate struggle for survival soon evolves into something more complex, as Ryouka begins to experience strange phenomena that suggest reality itself may not be what it seems. With each new discovery, the stakes grow higher, and the two childhood friends must rely on each other more than ever to uncover the truth behind their predicament and find a way to safety.