The Fourth Key

"Wheee!" 

Wally didn't know what overcame him as soon after, he was blindly enjoying the rides, giggling like a toddler from time to time. 

"This place is… pretty dangerous," Wally said. "I… have to double-check its safety."

"Wheee!" 

A day later, he slowly came to a halt, looking around to say, "Hmm, I think I missed something in my inspection before. I… I have to check it again." 

"Wheee!" 

"It's been two days already," Sterlena said, noticing Wally look at her in surprise. 

"I remember that I had forgotten something…" Wally said after a moment of thought. "I think I'll understand it soon…"

"Wheee!" 

Two more days passed in such a fashion before Wally controlled himself, exiting the water slides as he gazed at Sterlena, saying, "The laws related to wisps are pretty strong here. I think I understand what you wish to tell me by bringing me here."