I was looking at photos of Chigasaki, Japan in Google Images when I saw a photo a smiling man with what looked to be a huge pink bump on his shoulder. I clicked for a closer look and learned that he is a katsugite, a person who helps carry one-ton Shinto shrines supported on wooden poles. The bump was a callus from bearing the load of the shrine.

SoraNews24 has an article about katsugite and their mikoshi dako.

There's no mistaking what causes these shoulder calluses, given that they're known in Japanese as "Mikoshi Dako", or "Mikoshi Calluses". Just as players of stringed instruments develop lumps of hard skin on their fingers from years of practice, these mikoshi carriers develop bulges on their shoulders, which actually help to reduce the pain of carrying the portable shrine due to the build-up of hardened skin. Rather than hide the large lumps on their shoulders, however, the men who have them wear them as a badge of pride; as a symbol of their unwavering dedication to the deity, the shrine and the larger community itself.