Nimoto (煮もと)
"Ni-moto" was one of the producing methods of "Nanto moro-haku," the sake (Japanese rice wine) that had a reputation of having the highest quality and grade from the mid-Heian period to the end of the Muromachi period.
In modern terms, ni-moto can be described as a high-temperature saccharification method, which falls under "ki-moto" (one of the methods for preparing the starter mash).
By simmering the moto (the starter mash) in a pot, its volume increased, and undoubtedly simmering must have been performed within a very narrow temperature range because the yeast would have been killed if the temperature was too high.
Since there were no thermometers at that time, it is obvious that the temperature adjustment fully depended on the brewer's sense, and this suggests the method was a highly skilled technique which demanded a lot of experience.