Chou Ginten (銀天蝶) is the Zashono Academy treasurer.
She was away for an extened trip before the first volume of the manga. As academy treasurer her duty is to provide funding to all school clubs, however if the clubs do not benefit the academy then she will shut them down. Her first act when she returned was to disband the solar powered car club because of their lack of success at bringing the school prestige, having constantly lost at the national tournaments, as well as closing down another 27 clubs.
She desires to shut down the Eiken club because it apparently does not have any clear reason for being and is a waste of currency.
After determining that Densuke Mifune was an important member of the Eiken club, and without him it would collapse, she formed a committee of club presidents to help try to get him to leave the club. That proved to be more difficult than originally thought as with each encounter the club president trying at that time would abandon their mission and join Densuke's side. Eventually this culminated in her taking matters into her own hands and using fraud to publicly frame Densuke, which resulted in Chiharu Shinonome volunteering to be expelled to save Desnuke.
After fighting his way up to Chou's office with the club presidents he swayed he was able to save Chiharu from being expelled along with a plethora of other people.
She went mad and threatened to expel multiple people at once, including ones she previously deemed benefical to the academy, that is before Kirika Misono showed up and revealed something horrible. It turns out that the board had been wasting the large amounts of money she had saved the academy on naughty restaurants. Kirika later points out that she was so focused on Densuke because she had fallen in love with him. Which is no surprise since practically every girl in the series has done the same to at least some degree.
Despite being so formal and sometimes superior in tone, Chou is actually from a poor family, and has identical quintuplet brothers. Living in this state would seem like the reason for her money concious nature.
She is usually seen with Isouda.