Sign languages are visual languages used by deaf communities around the world. They use manual communication and have their own grammars and vocabularies distinct from spoken languages. Japanese Sign Language uses handshapes, movements, and placements to convey meaning, along with lip reading. Terms like "tewa", "shiji moji", and "kusou" refer to sign language, finger spelling, and mouthing respectively. The document questions whether deafness is solely a medical condition or also a social identity, and whether a deaf Japanese person's identity is defined by their nationality or by their membership in the deaf community.