Mysterium (ミステリウム) is formed by vocalist Naoki and guitarist Yuki.
V. Naoki / G. Yuki / Support B. Atsushi
Bassist Atsushi officially joins.
V. Naoki / G. Yuki / B. Atsushi
Drummer Pocky joins. (Date unknown: after July 1998.)
V. Naoki / G. Yuki / B. Atsushi / D. Pocky
Some time in the latter part of 1999, Mysterium disbands.