Complex Heart takes place in 2008. Sato Sumire is a selective mute girl whose only goal is to live a peaceful, calm life. However, her quiet existence is disrupted when she’s accepted into Fuyukibo, a prestigious school. At first, everyone around her seems either harsh or cold, leaving Sumire to struggle with fitting in. She knows she has to warm up to them, and they to her, but her selective mutism makes this difficult. In an attempt to fit in, Sumire joins the school newspaper club. There, she begins writing small poems, which are featured as brief entries in the paper. These poems become her way of expressing herself, helping her connect with others despite the barriers of silence.

Will they warm up to her?