"Necessary conditions?" Tsunade asked. "What conditions?"
"Technically speaking, only one condition is missing." Mimi said, "The soul. The soul you want to revive must still exist."
"Grandma's soul?" Tsunade's mind worked quickly.
"That's right." Mimi said, "It's in the Underworld, but its exact location is still unclear."
"Can you locate it?" Tsunade asked.
"Of course." Mimi nodded confidently. "At least three methods."
"What three?" Tsunade continued asking.
"The first is the Marking Method." Mimi said, "Using the trait that the souls of the dead travel to the Underworld, we plant a tracking mark and continuously send navigational signals."
"As expected of you. So, did you find it?" Tsunade asked.
"More or less." Mimi said, not entirely certain. "There are rather a lot of suspicious locations."
"So?" Tsunade asked.
"So either the Underworld doesn't exist in one fixed place, or it's moving." Mimi said, "For some reason, the signal strength keeps cutting in and out, making it difficult to determine and lock onto the location."
Mimi had experienced a similar situation inside the Box of Paradise.
"What's the second method?" Tsunade asked.
"The Screening Method." Mimi said.
"Screening?" Tsunade asked. How was that supposed to work?
"Still using the traits of souls." Mimi said, "In the material world of reality, there's nowhere that can obstruct a soul's movements. The Underworld is the exception. It can refuse entry to souls. When a stone blocking the road suddenly appears on a broad, unobstructed path, a soul taking a detour becomes an extremely obvious and significant anomaly."
"What if it doesn't obstruct them, but absorbs them instead?" Tsunade asked.
"Wouldn't that be even more suspicious?" Mimi said. "No matter what action the Underworld takes, the result is predetermined."
But the Sage of Six Paths was very clever. He had sealed off the Underworld and