That is Japanese for "Mountain Haze" and, according to YOYA KAWAMURA (1739-LIFE-1990), it is the only submarine-borne aircraft built anywhere whose primary role was offensive missions. This was the Aichi M6AI seaplane and in its early configuration, could jettison the floats for combat ... that must have made a return landing by the mother submarine a bit difficult.

More on this in a later KTB Magazine.