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.
I... I see.
هـ-هكذا إذاً
A-Ach so.
Entiendo…
Vale.
Ah bon… d’accord…
E-Entendi.