The first blade spirit to join the Demon Blade, Hachi is based on the real-life story of Hachiko in Japan. The loyal dog waits for his master each and every day, even after his master died. 

In the series, Hachi is the spirit of Loyalty, and due to his legend and story growing over the years, they gained the ability to grow larger. This ultimately was a foly on the part of Ino trying to in her own act of loyalty to her sister, to release Hachi to help find her sister in Tokyo. When Hachi’s power failed to be manageable, he began to run amok in the city streets, and it caused Tetsu to step up and learn how to wield the blade to stop Hachi.

In the midst of the chaos, Hachi began to hear the dark words and hate sent to him, and his spirit began to corrupt into becoming a Black Shulk, the spirit of an evil dog. But Tetsu, in observance, was able to see the pain the soul was in and showed it that love is still there to be found. Reminding him of the love his former master showed. Hachi returned to normal and willingly added his spirit to the blade.

While a blade summon, Hachi tends to be overly eager to appear and get both attention and food from Tetsu. But is willing to guard them for all time.