Kao to Koe no Ii Senpai ni Kawaretemasu.

Synopsis

"What a shame, Michika. I already know your weakness." Michika, who's got a thing for voices, is completely under the spell of the smooth-talking, sadistic student council president. Knowing she can't resist his voice, he tells her, “Pretend to be my girlfriend”...!? He’s ridiculously selfish, but she just can’t say no! A comedy full of teasing and mind games!(Source: PR Times, translated)