This Proto-Japonic entry contains original research. The reconstruction in this entry is based on published research, but the specific form presented here is not found in prior works.
In attested texts, this is attached to the form traditionally known as the 未然形(mizenkei, “irrealis or incomplete form”) of verbs. Perhaps also existed in reconstructions such as *naru(“to be”), *maparu(“to spin”, intransitive), etc.