Uso no Tsukenai Otoshigoro

Across Japan, adolescents are falling victim to a peculiar epidemic known as "dissociative true feelings." While not fatal, this mysterious condition causes an alter ego to surface whenever the host becomes emotionally agitated, forcing them to vocalize their deepest thoughts without any filter or pretense. Among those afflicted is Satsuki, a second-year high school student and the twin sister of Sayoi. Following a traumatic incident during her middle school years, Satsuki developed the syndrome and lost her natural voice entirely, leaving her capable of speaking only through her unfiltered, honest alter ego. Determined to shield her vulnerable sister from further distress, Sayoi has spent years strictly avoiding any interaction with boys. Her carefully constructed isolation is shattered when she crosses paths with Shougo, a young man who suffers from the exact same affliction. As Sayoi is drawn into his world, the protective walls she built begin to crumble, setting in motion a chain of events that will inevitably transform the fragile dynamic between the twin sisters.