The party first encountered Kibo in the run Dream Eater. He was the yumekui eating the hopes and dreams of the villagers of Xiaolu.
After defeating the yumekui, Yoshi determined to reform him. During the Night of Gates Yoshi named the demon Kibo and worked with Lijuan and a Baku to search for other sources of sustenance for Kibo.
Kibo has been a helpful presence in the dream plane, often to his detriment. For instance, in Dream a Little Dream he relayed a large amount of information about the Marked to Yoshi.
The protagonist in the children's story of Yoshi and the Yumekui is based on Kibo.
Takanata read the I Ching for Kibo, and is somewhat disturbed by what it means for a demon to no longer be following his path.
The GMs imagine Kibo as looking kind of like this.