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.
There's only one thing I wanted 
to learn via this incident...
هنالك شيءٌ واحد فحسب أردت
معرفته من هذه الواقعة
Ich wollte bei diesen Vorfällen
nur eines herausfinden.
Il n’y a qu’une seule chose
que je voulais tirer de cet incident.
C'era una sola cosa che volevo sapere
Só há uma coisa que eu queria
aprender com esse incidente...
Главной моей целью
было совершенно другое.