Uso no Tsukenai Otoshigoro

In Japan, an unusual illness known as "dissociative true feelings" has spread among teenagers. While not life-threatening, it causes an alter ego to emerge when a person becomes emotionally stirred, revealing their genuine emotions unfiltered. Satsuki, a high school sophomore, contracted the condition after an incident in middle school, which also left her unable to speak normally. To shield her sister, Sayoi, from the condition's complications, she has avoided interaction with boys. However, when Sayoi encounters Shougo, another individual affected by the same syndrome, the dynamics between the sisters begin to shift.