Turns out the one spreading the rumors was Hashimoto, who did so at the behest of Sakayanagi. Shortly thereafter, Sakayanagi appears before Class C and she informs them she has evidence regarding the rumors about Ichinose.
What you did won't vanish 
because you ran from it.
ما أقدمتِ عليه لن يزول بهربكِ منه
Wenn du wegläufst,
macht es das nicht ungeschehen.
huir no hará desaparecer tu delito.
huir no hará desaparecer tu delito.
Même si tu fuis,
ton crime ne disparaîtra pas.
Puoi fuggire quanto vuoi, ma il reato 
che hai commesso non svanirà.
Seu passado não vai desaparecer
só porque você fugiu dele.
Правда не изменится от того,
что ты бежишь от неё.