Not much is known about Chikage yet as her appearances in Magic Kaito have been limited to the first chapter of Volume 1 and the animated special Magic Kaito: Kid the Phantom Thief. In the manga it is implied she was aware of Toichi's secret life as Kaitou Kid and that her son, Kaito, discovered Toichi's secret for himself. She acctually knew
It has been suggested by Conan that whoever is the mother of Kaitou Kid is is also the thief known as "Phantom Lady" because of a remark Kid made at the Ryoma Gunbelt heist. This is only conjecture though as Conan is simply thinking to himself and Kid neither supports or denies this idea. It is worth noting however that Chikage's updated appearance from the Magic Kaito TV special matches the hairstyle of the Phantom Lady.
Although not much is known about Chikage, it can be implied she has a mischievous side to her character because she tells Aoko about Kaito's one weakness: fish.