A multifunction IC card has compatibility with a multimedia card, an SD card, etc. The color change component is induced to change colors by addition of saliva andor by a change in pH of the composition. A headrest frame may include at least one headrest frame support that may be removably connected to at least one attachment connection attached to the head section of the chair frame. The elastic body has transferring-member-side contact portions contacting the first torque transferring member, shaft-side contact portions contacting groove surfaces of the axial groove of the male shaft or the female shaft, and a biasing portion for elastically urging the transferring-member-side contact portions and the shaft-side contact portions away from each other.