His strength was already astonishing, yet even when he put everything into it, the door did not budge!
Tetsu no Sosuke stared in disbelief. "How much does this door weigh?"
Yuichiro was strong and sturdy too, with plenty of stamina. He joined Tetsu no Sosuke in pushing, but the door still did not move an inch.
"No, that doesn't make sense. If there's a door, why would it be sealed shut?" Yuichiro had recovered from his fear and muttered, "They left an entrance, which means people were meant to come and go. Otherwise, why make a door? They could've built a wall. Maybe there's a mechanism? Or maybe it's a tomb. A tomb only needs to be entered once, so sealing its door afterward would make sense."
But the moment he mentioned a tomb, fear crept back over him.
Tetsu no Sosuke rolled his eyes at the spineless boy. Then he spotted a small opening a little above the center of the door.
It was about an inch long and very narrow!
Tetsu no Sosuke reached out and felt it. "A keyhole?"
He did not have a key.
And yet it looked strangely familiar.
Yuichiro suddenly had an idea. "Could it be for a sword?"
Tetsu no Sosuke caught on at once. With a metallic ring, he drew Sunblaze and cautiously slid its tip into the opening. As he pushed it deeper, the fit grew tighter until there was no gap at all.
The instant the blade went in up to the hilt, a click sounded inside the door.
It sounded just like a key sliding into a lock.
Tetsu no Sosuke's eyes lit up. But when nothing happened after a moment, he tried turning the hilt.
It turned!
He twisted it to the right. It moved only a little,