Xiao Yi and the others shook their heads.

"I am the guardian of these ruins," the ancient giant said in a deep voice. "A great secret is hidden here. Only the true guardian can master this secret."

Hearing the guardian's words, Xiao Yi couldn't help but feel a strong sense of doubt and curiosity. What exactly is this secret? How does it relate to these ruins and the tower? Are they really the only ones who can hold this secret?

"Now I have told you the secret." The ancient giant's voice grew weaker and weaker. "You can choose to leave, or stay and continue to search for the answer."

Xiao Yi, Yuri, and Lili looked at each other, thinking about their next move. They knew that this ancient guardian must be the key to uncovering the truth.

"We need more information." Xiao Yi said in a deep voice, "We decided to stay and continue looking for answers."

A glint of appreciation flashed in the ancient giant's eyes. "Very good, you made the right choice," he said calmly. "Within these ruins lies a mysterious object known as the 'Key of Time and Space.' Only it can truly unlock this secret."

The Key to Time and Space? Xiao Yi and the others were startled. This term had appeared in some ancient books and was said to possess the power to travel through time and space. Could this ruin be related to traveling through time and space?

"Where is the Key to Time and Space?" Yuri asked in a deep voice.

A sly glint flashed in the ancient giant's eyes. "It's at the very top of this tower," he said calmly. "But to get there, you'll need to solve a series of puzzles and mechanisms."