Around this time, the band's lineup is as follows. It's unclear if any member changes occurred before or after.
V. JUNICHIRO ENDOU / G. KANENORI SAKINO / G. MASAKI MIYAGAWA / B. YASUYUKI KAIZUKA / D. TAKAHIRO MURASHIMA
According to LES ENFANTS TERRIBLES, GRAND SLUM was formed in 1987 around a former guitarist of GRAZIA (or possibly two former guitarists). GRAND SLUM is only known to have had one guitarist, MASA, but he is credited in that band's demotape as MASAHIRO NOMURA, which implies that he is not the same person as MASAKI MIYAGAWA. Details are unclear.
(Just as a confirmation: GRAND SLUM also has a drummer named TAKA, but he is credited as TAKASHI OHBA, implying he is not the same person as TAKAHIRO MURASHIMA either.)