On the way back, Gu Mengmeng secretly gave Lea 15 woven little balls made up of rattan. The balls were empty so Gu Mengmeng placed the opened chilli in the balls. Then, Lea handed them to Ian and asked him to send people to hide those balls. The exact hiding locations of the balls were unknown, let alone Gu Mengmeng, even Ian himself did not know.
This was why Gu Mengmeng dared to give 15 slots because she predicted that they would not be able to get back a portion of the balls.
Gu Mengmeng took out a woven little ball from her arms and shook it twice before saying, "There are 15 of this kind of balls scattered across the forest at the back of the mountains. Before sunset, the people who comes back with the balls will be able to join Saint Nazaire."