Jury's out. While >>10692131
is correct and that Maria's identity was bought from a boy student, we've never actually seen any evidence of Maria's gender.
However, since that particular scene was several characters throwing out random gag "admissions", not to mention Chiri-chan being hauled off by cops on apparently murder charges and Harumi being dragged away by sports club recruiters (both "never seen again"), the whole thing is dubious at best.
In other words, continue fappage until otherwise dictated.