In order to investigate Nagi's plans, Chie answered Sergay Wáng's call to become a member of the Artai Otome Squad, the Valkyries. Ever since Schwarz launched their invasion of Windbloom and Artai's taking control of Garderobe, Chie seemed to be driven by the motive to get inside Nagi's plot. This is evident when she questioned whether Sergay was unhappy that she was joining his crew, but he expresses that he can feel calm now that he had her on the team. Chie served as Sergay's second-in-command during the operation to capture Mashiro, and received a shock when she stopped for a bit and contradicted the orders given through the Cursed Obsidian (呪詛の黒曜石 Juso no Kokuyōseki) GEM. In the final battle she takes a blow for Arika from Tomoe but survives despite the destruction of her robe. It was revealed that she was able to do this thanks to the 'Spiraling' done by Shiho Huit, Lilie Andean, and Yayoi Alter that removed the robe's inbuilt restriction on disobeying orders.
Chie, now with the surname Hallard and having a larger role, is a Pearl at Garderobe and is 2nd member of the Trias, a group of three Pearls that deal with student discipline. When Akane left, she became the leading member of the Trias. It is interesting to note that in My-HiME, both she and Aoi made up much of the comedy in the series; while in My-Otome, they have more serious and dramatic roles.
She is very boyish and often carries a blue rose around. She is from the Aries Republic and seems to have some relationship with Aoi, paralleling their relationship from the first series. Chie remains calm and tries to help out whenever she can and balances out Shiho's aggressive behavior when dealing with student discipline. In episode 15 she tells Nao that she met Aoi when she started attending Garderobe. When Nao's gang was about to torture Miya's gang for attempting to rape Arika, Chie and Aoi showed up on the scene in which both Nao and Chie later took in Miya to interrogate. Later on, she said she was out on a date. When Mashiro was feeling depressed due to Takumi's words, Chie suggested to Aoi to bring in Arika to cheer her up which works and pulls both out of their depression. Chie was also aware that Tomoe Marguerite was involved in numerous plots to take out Arika Yumemiya but rather than report Tomoe she orders her to stop it. Despite knowing of the fact that Erstin Ho was injured during another plot, Chie kept silent about it for unknown reasons. At the end, it is revealed that she is Major Chie Hallard, a leader of Aries forces.
She has taken it upon herself to infiltrate the ranks of the Schwarz-controlled Valkyrie Otome. She visits the unconscious, seriously injured Aoi in a hospital bed before leaving for her mission as a Valkyrie. In the end, she is reunited with Aoi and arrests Nagi.
In the manga version of My-Otome, Chie's role is far smaller. Without the antagonism of Tomoe or the existence of the Valkyries, both of which were major plot points in which her anime counterpart had a part to play, she becomes mainly a background character. Her importance is further downplayed by the fact that she still uses the standard Pearl Robe whereas her fellow members of the Trias use Meister-level Robes.
She is still seen in the "group shot" of the Materialised Otome ready to do battle, though, and is seen briefly "dealing with" Shiho Munakata, offering a "taste of a real oneesama" as the Otome fight with the resurrected HiMEs, to the embarrassment of both Shiho Munakata and Shiho Huit.