Chapter 3

Demon Sword is the third chapter of the Seinen manga Eiyū Kyōshitsu.

Short summary
Arnest recalls some memories of when she first approached Asmodeus while training. Angry, she goes to the academy cafeteria and Blade decides to sit with her. Arnest then admits that Blade is better than her and apologizes for doubting him however, Blade asks her to not mind it since they're friends. Flustered, Arnest goes to her room but was spotted by a student entering her room.

Full summary
Chapter 3 opens up with a flashback; a young Arnest sneaks into a dark room after unlocking its door with a set of keys she most likely stole. There, she finds a huge, chained sword and, curious as she is, tries to touch it. Suddenly, a black mist completely engulfs her entire body and causes her to faint. Her father then enters the room and is shocked to find his daughter lying on the floor. He picks her up but is even more shocked when he sees the sword that was once chained, unsheathed. After an unknown period of time, Arnest finally wakes up in her bed, with her hair now completely red and father standing by her side.

At some point after Arnest inherited the demon sword, her father starts recounting that the sword she is holding is  the demon sword Asmodeus that has been passed down from ancestor to ancestor for many years and that it was considered a blessing even greater than kingship to the House of Flaming when it was sealed. He continues by saying that the owner of the sword will become the next head of the Family and that that will be her, and informs her that the sword, which thirsted for blood and slaughter, was sealed because he didn't want to burden her. Arnest's father then explains to her that because she was cursed by the demon sword, her hair turned red, just like the sword's very first owner, the first head of the House of Flaming, and that just like her ancestors, who, in order to fight the curse, developed an iron will to control and maintain themselves, she must always be in control of herself and continue fighting the demon, who will always be looking for a chance to take over her body, inside of her and defeat it, to which she agrees.