New idea! The maintenance cost is low! Charcoal rocket stove 

It consists of Oga Bincho charcoal + wood stove + rocket stove.
It is a stove that can be used in condominiums, apartments, and small rooms because it has no smoke, soot, tar, or odor.
Due to soaring fuel costs, we made it to reduce the heating cost of our living space of 31 tatami mats, but the result exceeded expectations.
Since my job is a gardener, I also have to cut down trees and it is easy to obtain firewood, so I am thinking of using only firewood in the future, but until then, I will use this Oga charcoal.
* Oga Bincho charcoal is made by solidifying sawdust and burning it as Bincho charcoal. The usability is the same as the official Bincho charcoal.
* Ventilation is done in parallel. I have never experienced any discomfort such as smoke, odor, or headache.
Later the chimney will be connected to the outdoors.