Chiharu Harukaze is a member of the student council. Secretly, under the alias of "Haruko", she works as Sakuya's maid. Although nobody in Hakuo is aware of that, in exception of Aika Kasumi, who found everything about her out soon enough.
(Source: Wikipedia)
In the 3rd season she no longer works as a Sakuya's maid, instead she now works as a sales clerk in a video store. She is staying in Nagi's boarding house as one of the tenants.