Here’s a photo of the classroom in a juku in a relatively wealthy neighbourhood in the southwest of downtown Tokyo.
From my visits to numerous juku around the country, a number of things are typical about this particularly classroom.
The first thing would be the nearly ubiquitous world map on the right-hand wall, accompanied of a similar map of Japan in this case.
Nest, this is an example of a juku that occupies space that was intended for some kind of office/commercial use. As the slanted wall/ceiling and the use of a partition on the right to block off the next classroom suggests, this was not intended as a classroom.
Not visible in the photo are two more rows of desks, this classroom thus accommodates about 16 students and classes at this particular juku typically consists of 8-12 students.
The classroom furniture here is the nearly-universal Kokuyo furniture that will be familiar to anyone who visits Japanese schools regularly as well