Last time, Katsu finished his mission and give the antidote to Ally with a note attached. After he hides and is comforted, but she thinks Ally should be the one.

A few days later, Ally is back to work and that person appears again. Katsu appears. So you appear after being run off by the law? Impostor replied. I never thought you would imitate me. Katsu replied. The impostor glared Katsu. Which gives me more the right to kill you! Katsu yelled. Katsu has appeared! Arrest him! Rin yelled. Rin you or the authorities can not catch or contain me if you tried. Katsu replied. Katsu smiled with crimson eyes. Katsu sped up and unsheathed Higanbana. The impostor unsheathed his Higanbana as well. Whose sword will kill who? Mine or yours, better think wisely. I'm itching to cut your head clean off your shoulders. Katsu replied. Commander Roselite, what happened to Commander Yoshida? Emilia asked. I don't know myself, but it's terrifying me as well. Ally replied. The imposter backed away. Cosmos opened a portal. Katsu slashed the portal back open. Don't think you can run away, you are not going to leave alive. Katsu replied. , this is not good. Hironori replied. What do you mean? Ally asked. He has tapped into Higanbana's full power some way. He is engulfed into his hatred toward the impostor who nearly killed you, Ally. Hironori replied. Don't run! Katsu yelled. So you think you can cut me head clean off my shoulders? Impostor asked. You won't be the first or the last. Katsu replied. Katsu sprinted over and tapped the impostor's Higanbana and sent them flying outside. Katsu jumped after him and landing on the ground, causing a crater on the ground. The whole sky turned black. What happened? Kaoru asked. This is an Ira Spell a high leveled one at that. Ally replied. Slash of the Wrath of the Dragon Queen! Yu yelled. Wait, I can see again. Katsu replied. Katsu raised his arms and did a straight strike. The impostor evaporated and their fake Higanbana. Katsu turned around. Thank you, miss. Katsu replied. She vanished. Did you see her face? Hironori asked. Vaguely, I feel we might meet her aga... Katsu replied. Ally ran over and caught him before he fell. This is what Higanbana meant. Katsu thought.
The end of Part Four.
See you in December.