Uso no Tsukenai Otoshi Goro

The world is plagued with the strange illness, [Voice] that affects teenagers. But when one's feeling is disrupted, a "bunshin" or a clone will appear and it will say everything you truly feel.
However, this illness does not pose any danger to one's life. Satsuki, a 2nd year high school developed this illness during that "incident" during her junior high school. Ever since then, Sayoi became protective of Satsuki and keeps anyone from approaching her. One day, they met Hiyama, another teenage boy who has the same illness. After meeting him, the twin's relationship started to change?!