These "Mikoshi Dako" are the badges of honour from a Japanese festival soranews24.com

At the heart of the festivities is the mikoshi, the portable Shinto shrine that houses the deity, which makes its way around town on specific dates each year.
Participating in the festival as a mikoshi load-bearer is something locals might do once in their lifetimes, or they might do it every year for decades.
▼ This is what results from bearing the weight of a Japanese festival.
There’s no mistaking what causes these shoulder calluses, given that they’re known in Japanese as “Mikoshi Dako“, or “Mikoshi Calluses“.
Like the Japanese, these men wear their calluses with pride; as a sign of religious dedication.