The “most correct” names seem to have been Merry Go Round from 1990~1998 and Merrygoround (1999~2003). Those two names were used on the vast majority of material during those times, with alternate spellings popping up occasionally enough that they can be attributed to error.
At some point (details unknown), guitarist KEN and bassist SHIN (シン) secede and are replaced by DEAD and YASUHISA (ヤスヒサ), respectively.
Vocalist Harry (破麗威) also changes the spelling of his name to Harry (葉里衣) at some point.
There is also said to have been a guitarist OSAMU, bassist HISANORI, and drummer KA'SHI at some point. They would have likely been members during this 1990~1994 period, but further details are unclear.
V. Harry (破麗威) / G. KEN / B. SHIN (シン) / D. TOHRU
V. Harry (葉里衣) / G. DEAD / B. YASUHISA (ヤスヒサ) / D. TOHRU
Merry Go Round pauses activity
Presumably, all members except for vocalist Harry (葉里衣) secede, and the band pauses activity as a result (details unconfirmed).
Merry Go Round resumes activity.
Vocalist Harry (葉里衣) changes his name to KAZUMA (真) and returns with all new members for a “reborn” Merry Go Round.
V. KAZUMA (真) / G. HIDENO / B. Sakyou (左京) / D. KYOU (キョウ)
Bassist Sakyou (左京) secedes and is replaced by Junna (准那).
V. KAZUMA (真) / G. HIDENO / B. Junna (准那) / D. KYOU (キョウ)
Note: The band was involved with several companies over the years, and the context of each label's involvement often differed from release-to-release (see each release for details). Based on product codes and liner notes, MEDICAL BEAT and YENBANYA seem to be the two constants—at least until the year 2000. In those two cases, the “official” relationship was never made clear, but it seems that MEDICAL BEAT could be considered the band's “label”, and YENBANYA the band's “management”.
With the release of -“S”-, the band begins a major distribution deal through BANDAI MUSIC.
Bassist Junna (准那) and drummer KYOU (キョウ) secede.
V. KAZUMA (真) / G. HIDENO
The band's official fanclub, PSYCHEDELIC DRUGS, opens.
MAXXX and TOHRU begin as support bassist and support drummer, respectively.
V. KAZUMA (真) / G. HIDENO / Support B. MAXXX / Support D. TOHRU
By this time, with the release of Akaiito, the band's major distribution deals seem to have ended.
The release of REDDISH COLLECTORS NO DEAD ARTIST is the last appearance of MEDICAL BEAT; it seems that the self-run label dissolved sometime in the next year.-label
Twoman vs Art Marju Duchain is held.
Bassist MAXXX officially joins, and drummer Shoji joins.
V. KAZUMA (真) / G. HIDENO / B. MAXXX / D. Shoji