These are called the "Japanese Design 3 Pairs Sonic Socks"
These are a bundle on the Sega Shop in 2019, and should be about 13 dollars for the set. They are adult size socks. Each pair is black, with woven-in blue Sonic designs. The top pair has a classic Sonic face with his name spelled out in Japanese letters under it. The left pair has a blue toe & scattering of the same Sonic face. The right pair has a white toe, heel & stripes under the foot. That Sonic design is the 'side jumping' classic Sonic that was mostly seen in Japan. So, the set sort of lives up to the 'Japanese design' label.
Woven-in designs don't wear off/wear out easily, and adult sizes are always a good sign. 13 for 3 pairs isn't a super great nor super bad price. The sturdy & decent design plus ok price makes these an all right set to get.