Sugaguchi-Goiwai is a traditional form of song that dates back to the late Edo period in the Sugaguchi district of Otomocho in Tohno City, Iwate Prefecture. This unique style of song, in which the male part and the female ballad are sung simultaneously, has been passed down and is sung at various celebratory occasions such as weddings and new home celebrations. However, there are still many aspects of this type of song that remain unknown. In particular, it is extremely interesting how songs begin with the male and female parts out of synch but end with them in harmony, and no detailed survey has so far been conducted on the specific methods of ensemble. This means that the basic features of Sugaguchi-Goiwai have not yet been grasped. In this research, we transcribed a number of recorded performances and analyzed the multi-temporal aspects of Sugaguchi-Goiwai based on its simultaneous harmonizing of two songs. Also, we visited Tohno in order to observe performances and interview performers with a view to clarifying the actual condition of ensembles.