Tetsuko (テツコ) is a prominent character of the Mamonaku Kaien series.
Tetsuko is in charge of the Drama Club's stage lighting, which is mostly handled by pulling up the brightness on her cellphone and pointing the screen towards the stage.
She is extremely laid-back and seems to have little concern for her duties in the club. Her trademark catchphrase, "I'm leaving," seems to resonate to the others as a sign that Tetsuko simply does not want to be there. But Mary wonders if that is actually true.