Less a direct crossover and more a thematic one.
You know all those stories where Queen Serenity is a tyrant, the Moon Kingdom was a fascist state, and Beryl was either a rebel or just less evil than Serenity was? Well, this is kinda like that. You see, 10,000 years ago Beryl and Serenity pulled off a double-KO and sealed each other away into separate dimensions, now the seals have come undone and they both want a piece of Earth for themselves.
On the one hand, you have Queen Serenity. A just and fair ruler of what's left of the Moon Kingdom and the surviving Sailor Senshi. While she's not evil by any stretch of the term, she's decidedly Lawful Neutral and has this bizarre notion that if Earth were unified under her (benevolent) dictatorship all our problems would go away and we'd get a planet-wide utopia within a few years. So she and the Senshi decide to invade Earth "for the greater good", regardless of what we have to say in the matter.
On the other hand, there's Queen Beryl, a completely batshit insane demon overlord who doesn't rule her kingdom with an iron fist so much as she pokes it every now and then. Beryl is prone to selfishness and arrogance, much like pre-character development Laharl, but she's also very hands-off in her leadership; if she invaded Earth, she'd probably bring down the governments and then let chaos do the ruling for her, leaving her subjects to live more or less as they please. Beryl invades Earth partially because Metallia needs to be revived, partially because she wants something to do, and partially just to keep Serenity from sinking her claws into it.
Neither of these two sides really have Earth's best interests in mind (though Serenity thinks she does), but neither of them are really evil either. However they've both made the mistake of starting their invasion over a leyline convergence in Tokyo's Azabu-Juuban district, where a small group of girls who happen to be a mix of reincarnated demon lords and Senshi just happen to be living...
You know all those stories where Queen Serenity is a tyrant, the Moon Kingdom was a fascist state, and Beryl was either a rebel or just less evil than Serenity was? Well, this is kinda like that. You see, 10,000 years ago Beryl and Serenity pulled off a double-KO and sealed each other away into separate dimensions, now the seals have come undone and they both want a piece of Earth for themselves.
On the one hand, you have Queen Serenity. A just and fair ruler of what's left of the Moon Kingdom and the surviving Sailor Senshi. While she's not evil by any stretch of the term, she's decidedly Lawful Neutral and has this bizarre notion that if Earth were unified under her (benevolent) dictatorship all our problems would go away and we'd get a planet-wide utopia within a few years. So she and the Senshi decide to invade Earth "for the greater good", regardless of what we have to say in the matter.
On the other hand, there's Queen Beryl, a completely batshit insane demon overlord who doesn't rule her kingdom with an iron fist so much as she pokes it every now and then. Beryl is prone to selfishness and arrogance, much like pre-character development Laharl, but she's also very hands-off in her leadership; if she invaded Earth, she'd probably bring down the governments and then let chaos do the ruling for her, leaving her subjects to live more or less as they please. Beryl invades Earth partially because Metallia needs to be revived, partially because she wants something to do, and partially just to keep Serenity from sinking her claws into it.
Neither of these two sides really have Earth's best interests in mind (though Serenity thinks she does), but neither of them are really evil either. However they've both made the mistake of starting their invasion over a leyline convergence in Tokyo's Azabu-Juuban district, where a small group of girls who happen to be a mix of reincarnated demon lords and Senshi just happen to be living...