Info: "“Valkyria” is a small doujin series by Takeuchi Takashi, first published in 1998. It is a story of revolving around valkyrie who fight using the souls of their hero.
However, for valkyrie, the heroes are more than just a weapon. Residing in their sword, Valhalla, they are their lifelong companions, their comrade-in-arms, their partner, and their destiny. For them, to live and die by the sword is more than just a warrior's phrase; it is their entire purpose."