"What the heck?"
Fushimi Roku was startled, afraid he had accidentally pressed some button. He quickly got up, lifted the mattress, and only then noticed a small iron box underneath.
Worried it might contain a bomb or poison gas that would trigger upon opening, he cautiously wrapped the iron box in the mattress, carried it all the way down to the apartment lawn, and placed it on the grass.
Better safe than sorry.
Fushimi Roku used a clothes-drying rod to nudge open the lid of the iron box. The anticipated explosion or poison gas didn't occur. From a distance, he stood on tiptoe to look inside and saw a card.
Fushimi Roku breathed a slight sigh of relief, leaned in closer to take a look, and found that the card was an Invitation Letter, with a string of gilded numbers printed in the center, likely coordinates, and a small line of text beneath:
"Looking forward to your visit again."
