Chen Mo started distributing the work to the three of them after going through the design concept.
Everyone was more or less familiar with their jobs after working on Warcraft and Wulin Legend without needing Chen Mo to say much.
Chen Mo re emphasised the importance of the story for Onmyoji.
Onmyoji did have an IP, it was a novel by Baku Yumemakura under the same name. However, the novel wasn't super influential in China either, and the biggest contribution of the novel to the success of the game was the story.
Of course there would be a lot of work involved remaking the novel, and Chen Mo didn't need to do that as Zheng Hongxi could fill out the rest after receiving the main gist of the story.
Moreover, most of the monsters and characters in Onmyoji were based on folklore from the Heian period taking inspiration from Konjaku Monogatarishūt, so it wasn't hard for Su Jinyu and the others to grasp the concept.