A second-year middle school girl whose emotions never show on her face. Her classmate Ota constantly plays pranks on her to try and change her expression. However, like she's wearing a mask, her face barely changes from its default state no matter what happens. Even when she's laughing or feeling afraid, she only trembles slightly. That said, she isn't completely devoid of expression.

A boy who plays various pranks to somehow draw a different expression out of the stoic Kashiwada. His methods are quite diverse. In stark contrast to Kashiwada, all his emotions show clearly on his face. Kashiwada often uses this to turn his pranks back on him or tease him instead. He considers his expressive face to be a bit of a complex.

Ota's classmate. He often appears alongside Sata. While not as extreme as Ota, his expressions are quite readable, and he serves as a comedic character. He seems to be even less bright than Akito.

A classmate of Kashiwada and Ota. He is good at his studies and popular with the girls. While not to Kashiwada's level, he is quiet and often maintains a poker face. He is sharp enough to notice that Kashiwada and Ota like each other. He plays the straight man, calling out Tadokoro whenever he acts oblivious.

A girl who is a self-proclaimed fan of Kashiwada; her joy in life is observing Kashiwada's minute facial changes. She is wary of Ota, who frequently approaches Kashiwada. Like Ota, her emotions show easily on her face. Surprisingly, she has a curvaceous figure. Judging by how she occasionally blushes at Tadokoro's words, she seems to have feelings for him. She is the class representative.

A beautiful, friendly, and popular girl with a blonde ponytail and a snaggletooth. She is one of the few people capable of reading Kashiwada's expressions.

Like her brother, her emotions show clearly on her face. They have a typical sibling relationship. She loves playing pranks so much that she's nicknamed 'Crazy Ota' at her university.

A university classmate of Ota's sister. Like his younger sister, his face doesn't show much emotion and he is usually smiling, though his expressions change more clearly and frequently than hers. He cherishes his sister deeply and is therefore wary of Ota, who keeps pestering her with pranks.