I thought Japan had a relatively warm climate until my research into the era revealed that the Earth was hit by a small asteroid a few years before Yamabuki sets out on musha shugyō, which roughly gets translated into English as knight errantry. Yamabuki encounters colder conditions that we usually associate with Japan, even in the north.

The asteroid that his Earth was not large enough to cause a mass extinction–obviously!–but it did set up a lot of particles in the atmosphere that created what according to my readings induced a “mini ice age” with lower than normal temperatures. Of course, in my books, the people attribute the colder condition to the foxes who are always out to cause trouble.

The fact this was the case led me to emphasize the colder climatic conditions throughout the series.

Osaka Castle in Winter

In an era where we are concerned with global warming, calling attention to global cooling is a footnote that reminds us how precious our planet actually is.