Yes, Sex Android is definitely a goth band because most of their albums belong to the Gothic Rock genre, which is a core subgenre of goth music. Albums like Planet Venus and Sexaroid Capsule Schneider are examples of their goth sound.
Some of the other goth artists that are similar to them are Phaidia and †13th Moon†.
Sex Android is located in Japan, Tokyo, active in 1986 — 1988. You can find more information about Sex Android on their GothDB band page.