The trio moved deeper into the Ravine, the weight of silence pressing down harder than the dense canopy above. Kaito's mind buzzed—his body still trembling from the last battle, the Void's hunger gnawing at the edges of his consciousness.
Hina broke the quiet. "You're not saying anything, Kaito. Are you alright?"
He forced a nod. "I'm fine... just tired."
Riku, ever calm, glanced at Kaito with a half-smile. "You're far from fine. That 'Void' of yours isn't some ordinary Seiki. It's more of a curse than a gift."
Kaito frowned. "A curse?"
Riku's gaze darkened. "Seiki power comes with a contract—what we call a Yakusoku. It's a vow or condition that balances strength with a price. Without accepting this, your abilities are unstable and dangerous."
Hina's eyes narrowed. "Like what kind of prices?"
Riku crouched, resting his hand on a fallen branch, voice dropping to a whisper. "Prices can be anything: physical pain, shortened lifespan, emotional torment, or the risk of losing control entirely. Some pay with their sanity, others with their lives."
Kaito swallowed hard. "So... the hunger inside me, the drain on my body... that's the price?"
"Exactly." Riku nodded. "Your Void devours other Seiki, but in return, it demands something. If you ignore the debt, it will consume you instead."
Kaito looked down at his trembling hands. "How do I control it?"
"That's the trick," Riku said, standing. "You must willingly accept a Yakusoku—a binding vow that sets the rules for your power. It stabilizes the ability but always costs something valuable. Your freedom, your memories, your emotions, or even a loved one."
Hina glanced between the two boys, her aura flaring slightly with impatience. "Enough talk. How do we get out of this forest alive?"
Before Riku could answer, a chilling howl echoed nearby, and the ground beneath them trembled again. This time, a pair of glowing eyes appeared from the shadows—smaller, faster, and more cunning than the last beast.
Riku smirked. "Looks like your trial isn't over yet, Kaito. Time to put theory into practice."
Kaito clenched his fists, the Void stirring within him, whispering its hunger.
He took a deep breath. "Then I guess... I need to make a vow."