Four years ago, a large scale disaster in Tokyo claimed two million lives. The remaining thirteen districts of the city were isolated into the Tokyo Barricade Zone. Morisaki Harumi, an unruly kid with great fighting strength, is his family's sole survivor from the incident.
One day, in a traffic accident, Haru gets pulled into a world of violence and meets Mana, the girl who turned herself into an ancient sword.
Story ends at 12 volumes and continues into the sequel X Blade Cross.
This series provides examples of:
- Action Girl: Despite spending most battles as a sword, Mana is more than capable of holding her own in a fight.
- Battle Couple: Pretty much every Anathemea and their wielder to various extents.
- Big Bad: Jin Estaku is an alchemist-turned-Humanoid Abomination who created the Anathema and is the true main antagonist of the series.
- Bullet Time: Haru has the ability to perceive movements as much slower than they are. However, he can't move any faster, meaning if he can't tell where it will go, he can't avoid an attack. Whether it's a trait of his own, or a result of Kuushirou is debatable.
- Cain and Abel: The last time Haru saw his sister Aki she seemingly fell to her death during the disaster that devastated Tokyo. She's become an Anathema and The Dragon to Jin, wielded by Kuushirou's mindless body.
- Conveniently an Orphan: Haru lost his immediate family four years prior, during the disaster that destroyed Tokyo.
- Determinator: Although a less extreme example as some others, Kaori refuses to miss school for a cold because "For 3 years I've never been late or absent! My willpower will get me through!"
- Haru refuses to give up in spite of the odds that he faces.
- Lulu Rau uses a secret technique to move even after all her bones were broken and her tendon severed.
- Eldritch Abomination: Whatever the heck those...things are that came from the Yamato.
- Empathic Weapon: The Anathemea or "Guardian Blades", are swords that were once people, and can assume human form at will.
- Eyes Do Not Belong There: The Big Bad, Jin Estaku, has eyes on the palms of his hands.
- Grand Theft Me: Kuushirou, Mana's previous wielder, inhabits Haru's body. More than once he's fully taken over. Unfortunately for Haru, Mana sees this as the preferential outcome, though she's started to warm up to him.
- Living Weapon: The Guardian Blades are swords who were once humans.
- Wrecked Weapon: If their owners die or they get killed their blades shatter and they die as well.
- Loves My Alter Ego: Mana is very much still in love with Kuushirou, and openly prefers him to Haru.
- Naked First Impression: Mana, when she first wakes up. Also Naked on Arrival, since it's the first time the audience sees her as well.
- Powered by a Forsaken Child The Anathema were once people, sacrificed to create the weapons. Worth mentioning most were voluntary.
- Sanity Slippage: Kazunari suffers this as the first story continues.
- Sharing a Body: Kuushiro's soul inhabits Haru's body.
- Tsundere: Mana is a Type A towards Haru.
- What Year Is This?: Mana asks this once she wakes up fully, having been asleep for 360 years