Keiko first appears in the story "The Black Soul" (v.2 issue #13). When her grandfather was attacked and killed by criminals (her parents had both died some time before), Keiko was saved when Jei suddenly appears and kills all the criminals, but spares Keiko, saying "The Gods see no evil in you, little one." As Jei leaves the house, now in flames, Keiko runs after him, as she has nobody left.
Traveling with Jei, Keiko refers to him as "uncle". After Jei-san is killed, he transfers into Inazuma, who Keiko joins and continues on her journey (now calling the Jei-possessed Inazuma "auntie"). Later, after Inazuma is injured, Jei transfers over to Priest Hama and rejoins with Keiko.