After taking the key from the gatekeeper ninja on the left, Orochimaru walked up to the door.
As he inserted the key into the keyhole, a faint chakra glow immediately appeared. Around the keyhole, twelve different symbols emerged—"Rat, Ox, Tiger, Rabbit, Dragon, Snake, Horse, Goat, Monkey, Rooster, Dog, Pig"—representing twelve hand seals.
Orochimaru's gaze shifted slightly. This was the "combination lock" built into its design. Besides the key, the gate could only be opened with a sequence of hand seals that changed at set intervals.
Orochimaru calculated in a low voice as a string of formulas flashed rapidly through his mind, his expression incomparably grave. Once the key activated the door, he had to solve this special ninjutsu mechanism within ten seconds, or the barrier would automatically activate.
Fortunately, Orochimaru had come thoroughly prepared. Though he had been unable to directly obtain the hand seals needed to unlock the mechanism, he had learned the general algorithm from the Hokage's classified documents.
There was a saying that scientists were all mathematicians. In this world, there was naturally no such thing as scientists, but the principle remained the same. No one in all of Konoha could rival Orochimaru's mathematical attainments.
By calculating from the year, the time, and even the hand seals used last time, Orochimaru derived what he needed within five short seconds and swiftly began forming hand seals.
As his hands shifted, the symbols representing the seals lit up one after another. Then came a faint rumble as the doors opened to either side.
The corners of Orochimaru's lips curled into a somewhat sinister smile. He casually pulled out the key and tossed it back onto the unconscious Jonin, then strode into the building.
The doors closed behind him. The interior was brightly lit, having long since switched to electric