Valis

"Not to be confused with the semi-autobiographical novel by Philip K Dick, which you can find here."

A series of platform games by Telenet Japan.

In the first game, we are introduced to the main character, Yuko Ahso. She was an Ordinary High School Student, who had just gotten into a fight with her best friend, Reiko one day, when the armies of the Dark World invaded Earth and Dreamland, the three of which are parallel to each other. Upon discovering this, she was given the Valis sword by Valia, Queen of Dreamland, and told of her heroic destiny. As The Chosen One, Yuko must save Dreamland and Earth from the forces of evil. Reiko, unfortunately, has fallen in love with Rogles, who is head of the DarkWorld army, and so she also opposes Yuko in her quest.

Stretched out over four games, the series traces Yuko's adventures and tribulations, gradually gaining some depth but ultimately unable to escape the criticism for existing merely for the purpose of Fan Service.

This series had gameplay features vaguely similar to some of the older Castlevania series, but was otherwise unnotable except for it being pretty much "all about hot anime chicks in bikinis and schoolgirl outfits destroying things."

A word of caution before you get into this series: As Telenet went out of business (the entire Telenet catalog is now owned by Sunsoft), they licensed the rights to this series to another company that has turned it into a hentai production called "Valis X". Beware of this if you don't want to get into Not Safe for Work content.

Tropes used:
 * American Kirby Is Hardcore: Both versions of Valis III. Also, though not as bad, The fourth game, compared to this.
 * Ascend to A Higher Plane of Existence:
 * Amazing Technicolor Battlefield: The final battles in Valis II and Valis III both take place IN SPACE for no apparent reason.
 * Ancestral Weapon: The Valis sword and its counterpart, Leethus, which belongs to Glames, King of the Dark World.
 * Breast Plate: So... how exactly does a golden brassiere and miniskirt protect against anything, exactly?
 * Dark World: The actual name of one of the lower realms in the Valis cosmos, along with the Dreamland and The Real World.
 * Deadly Upgrade: According to Nazetti in the third game,  It sucks that this also ends up being entirely cosmetic, albeit awesome.
 * Fan Service
 * using Stripperiffic armor galore!
 * And don't forget the slide maneuver, which (in the Turbografx CD version) exposes the heroine's underwear.
 * Evil Counterpart: Reiko becomes the Dark Valis Soldier to Yuko's Valis Soldier.
 * Evil Is Visceral: Emperor Megas has lots of twisted bundles of huge biomechanical arteries underneath his armor and face.
 * Fan Translation: For Valis 1 Famicom and Valis II for X68000.
 * Franchise Killer: Valis X, which not only was a Hentai game, but a poorly drawn one at that. Not the glorious revival people were expecting...
 * Girl in A Box: Though it's actually an ice crystal, Valna in the third game who is  the princess of Dream World.
 * Heroic Sacrifice:
 * I Am Not Shazam: The heroine's name is Yuko, not Valis, in case you did not know.
 * Inconsistent Dub: So is it Cham or Char? Valis, or Varis? Syd of Valis renames Yuko to Syd in game, but the box and manual disagree.
 * Magic Skirt: Most versions of most of the games have this.
 * Mirror Boss: Reiko. That One Boss due to her spell, which hits the entire screen and takes off 48% of your life bar's capacity in damage.
 * Nintendo Hard: The third game after, arguably. Especially the Slippy-Slidey Ice World, which requires you, at one point, to jump on a moving platform (still slippery), quickly duck to avoid the suddenly low ceiling, and then use a well timed slide maneuver to get over a Pit Of Doom. And then you have to fight the boss.
 * Also, the fourth game (very hard to find that fourth game).
 * The first Valis is this all on its own, to the point where the Fan Translation has an optional easier version.
 * Panty Shot: The PC-Engine CD version of Valis 1 does this whenever Yuko jumps.
 * Rival Turned Evil: Reiko.
 * Robe and Wizard Hat: Valna, the one who fights using a magic spell, wears a robe (though not a hat).
 * The Chosen One: Yuko (and later Lena) are the ones who can save the world by wielding the Valis Sword.
 * Save the World: Of course the plot of the three games; subverted in the third game in that, by saving your world from the invading armies of the Dark World,.
 * Sequel First: The original Valis was the last game in the series that was remade for the PC Engine.
 * Shameful Strip: In the PC versions of Valis II, Cruel King Megas demands Yuko to strip down. She complies.
 * Super-Deformed: SD Valis (or Syd of Valis), which retells Valis II's story in a Cliff's Notes way.
 * Whip It Good: Cham.
 * Womb Level: The final level in Valis 4. The Big Bad even attacks by shooting giant fetuses at you.
 * The final level in 2 resembles an alien hive from the Alien movies. Also, Act 4 takes place in an organic-looking cave.
 * You Gotta Have Blue Hair: Yuko has blue hair, Reiko has purple hair, Valna has light blue hair, either Lena or Amu has purple hair.