Valkyrie

Valkyrie is a character from Adventure of Valkyrie series, she makes her debut in The Adventure of Valkyrie: The Legend of the Key of Time as the main protagonist alongside Kurino Sandra.

Profile
A warrior maiden in service to the Goddess who rules the Heavens.

While she has the strength of conviction to bravely face down whatever challenges confront her, she is also possessed of a merciful and meek personality, and she is unfailingly polite.

In battle, she attacks with exceptional sword skills and a variety of magic.

When the Demon King Zouna was reawakened and persecuted the people of Earth, she stood against him, ultimately defeating him.

After that, the Demon Kamuz also appeared, stealing from mortals the Golden Seed that grants any wish to use it to rule the world. Valkyrie descended to Earth once more to face this new crisis and restore peace, and after a long battle, she managed to seal Kamuz away.

Story
In the world of Marvel Land, people and nature lived in a harmonic coexistence. A large clocktower stood watch over them. An ancient evil was sealed away there, but no one was worried for those days were long gone...or so they thought. One day, the clock stopped working. One of the villagers attempts to fix it, but it was too late: Zouna, the evil wizard that can control time was freed and stolen the key to ensure he won't be sealed again.

Chaos and darkness fell onto the denizens as Zouna's powers were unleashed upon Marvel Land. Their savior came from the heavens: Valkyrie, a fledgeling maiden who vows to stop Zouna's terror. Along the way, she encounters the Sandra hero Kurino, and frees him from Zouna's curse. As she continued on her quest, she learns that a demon thief called Kamuze has stolen the Golden Seed. A mystical item and of high value, she and Kurino sought to get it back. After retrieving it, they head towards the castle where Zouna is said to rule. As they get closer, she falls into an illusion and faces Dark Valkyrie, a dark version of herself, in battle. After defeating her shadow, Valkyrie confronts Zouna in the deepest part of the castle. After a long fight, Valkyrie emerged victorious and Marvel Land is once again at peace.

Crossover Appearances
Project X Zone 3: War of Infinite Worlds

Valkyrie appears as a Solo Unit.

Project X Zone 3: Sacred Destinies

Valkyrie appears as a Pair Unit teaming up with Aty from Summon Night series.

Project X Zone III (RedTheHedgehog140) 

Valkyrie appears as a Pair Unit teaming with Palutena from Kid Icarus.

Project X Zone 3-D

Valkyrie appears as a Pair Unit teaming up with Lenneth from Valkyrie Profile.

Project X Zone 4: Fate at Hands

Valkyrie appears as a Pair Unit teaming up with Palutena from Kid Icarus.

Super X Dimensions

Valkyrie appears as a Pair Unit teaming up with Pit from Kid Icarus.

Namco X Capcom 2: Zeo

She is one of the characters from Namco side.