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.
Quit spreading these 
shitty rumors, Hashimoto!
كفّ عن نشر هذه الشائعات
!المقيتة يا هاشيموتو
Hör auf, diesen Scheiß
zu verbreiten, Hashimoto!
No inventes rumores, Hashimoto.
No te inventes rumores, Hashimoto.
Arrête de faire circuler
ces rumeurs débiles, Hashimoto !
Ehi, Hashimoto, 
smettila di spargere 'ste voci fuori di testa!
Pare de espalhar esses
boatos de merda, Hashimoto!
Кончай распускать
дебильные слухи, Хасимото!
หยุดปล่อยข่าวลือแปลก ๆ ได้แล้วเฟ้ย ฮาชิโมโตะ!