The Asahi Group（Yamauchi, 1986）consists of felsic crystal tuff, andesite lava and felsic lapilli tuff, and is divided into the Imaichi and Marubara Formations, in ascending order. However, it is assigned to the Nakano Formation of the Sakurae Group in the present study. The collapse structure filled with the Nakano Formation in the studied area forms the southwestern part of Sakurae cauldron. The Marubara Formation of the upper Asahi Group is not the infill associated with an independent cauldron, but is a part of the intracaldera fill of the Sakurae cauldron, even though Yamauchi（1986）inferred overlapping cauldrons of different ages in this area.