Okay, let's craft Chapter 37 based on Kurozane continuing his fight, Zephyr's sacrifice,
(Opening Scene: Kurozane dances precariously around the enraged Thornhide Beast, the Null Blade hissing as it scrapes against the creature's thorny hide. Astrid stands nearby, clutching the broken hilt of her sword, watching with a mixture of awe and fear.
The Thornhide Beast, wounded and desperate, roared with fury. It swung its massive claws, each blow capable of crushing bone. Kurozane, though agile, was tiring, the constant need for evasion and attack taking its toll. He knew he had to find an opening, a way to deliver a decisive strike.
Seeing Kurozane momentarily off-balance, the Thornhide Beast saw an opportunity. Instead of continuing its assault on him, it suddenly lunged towards the defenseless Astrid, its glowing yellow eyes filled with a primal intent to kill.
Before Kurozane could react, a blur of feathers shot through the air. Zephyr, Astrid's magnificent falcon, dove with incredible speed, intercepting the Thornhide Beast's attack. The creature's massive claws struck the falcon, a sickening crunch echoing through the forest. Zephyr cried out in pain, his wing twisted at an unnatural angle, but he had shielded Astrid, taking the brunt of the blow. The Thornhide Beast recoiled, momentarily stunned by the unexpected sacrifice.
Rage surged through Kurozane. He saw the injured falcon, Astrid's shocked expression, and the monstrous creature that had dared to attack his companion. Focusing all his fury and void power into the Null Blade, he lunged forward. The shadowy blade pierced the Thornhide Beast's thick hide, finding a vulnerable spot near its heart. The creature shrieked, a final, agonizing cry, before collapsing lifelessly to the ground.
Kurozane stood panting, the Null Blade dripping with dark ichor. He turned to Astrid, concern etched on his face. She was kneeling beside the fallen Zephyr, her hand gently stroking his injured wing.
"Zephyr…" she whispered, her voice filled with distress. But then, a strange calmness washed over her features. "It's alright. He'll be alright."
Kurozane frowned, confused by her sudden change in demeanor. "He looked… badly hurt."
Astrid nodded. "He is. But familiars… they are tied to their wielder's life force. Unless the bond is severed completely, they cannot truly die. He will regenerate, slowly, over the next day. It's a blessing… and a curse."
She then explained, her voice growing slightly strained, "However… if a familiar is killed, truly killed, a part of the wielder… suffers. The backlash can be severe."
As she spoke the last word, a trickle of blood suddenly ran from Astrid's nose. Her eyes widened in shock, and then, her body went limp. She swayed and collapsed forward, falling into Kurozane's arms.
Kurozane caught her, his surprise evident. He held the unconscious noblewoman, Zephyr's injured form lying beside them, the slain Thornhide Beast a silent testament to the brutal fight. The concept of familiars and their intricate bonds had taken a sudden, alarming turn.