Chapter 4: Vindicta(Vengeance)

She saw two demons trying to finish off Yui. Although she fought bravely, she couldn't fight them both, as they were much stronger than the others. Kouta, seeing this, flew at full speed and knocked them away from her with a single blow.
Kouta: GET AWAY FROM HER, BASTARDS!
Yui, panting, fell to her knees, exhausted.
Yui: B-be careful, Kouta... t-they're very strong...
Kouta: Yui! Grrr... I'll get paid for it!
Without thinking, she unleashed her full power. Her aura ignited in a deep purple glow, and a surge of energy shook the ground.
Demon 1: Hahaha, what can a mere rookie do to us? It's two against one, kid, you can't beat us.
Without responding, Kouta disappeared from the demons' sight and, in the blink of an eye, punched the first one with such force that it threw him against a mountain, leaving a crater. The second demon tried to attack him in the face, but Kouta stopped it with a single hand and punched him repeatedly until he was unconscious. When the first one staggered back, he managed to land a punch in Kouta's face, but he didn't even flinch. With terrifying coldness, he grabbed Kouta by the neck and was about to finish him off when...
Yui: K-Kōta... d-don't d-do it, please...
The glow in Kouta's eyes gradually faded. He glared at the demons and finally let them go.
Kouta: Get out of here before I change my mind!
The terrified demons fled without a second thought. Kouta was breathing heavily, but as soon as he saw Yui on the ground, he ran over and healed her.
Kouta: Why did they attack you? What happened?
Yui: W-well... they wanted to open a crack in the barrier... I tried to stop them, but...
Kouta: Those damn demons... I won't stop until I'm done with them.
Yui: D-don't worry... let's forget about them for now.
Kouta sighed, picked her up, and flew her back home. During the trip, Yui fell asleep in his arms. Upon arrival, Kouta laid her on his bed and secured the house before heading out to train.
As he trained, he felt frustration. He knew he needed more power. He pounded the ground furiously and released a massive amount of energy, a shockwave that even Haruto could feel from a distance.
Haruto: What the hell...? That boy... he's progressing rapidly.
Kouta, pushing himself to the limit, managed to increase his power beyond what he thought possible. His energy now rivaled that of a mid-rank Demon, but the effort was too much, and he collapsed.
When he woke up, it was already dawn. Yui, worried, had been searching for him, and when she managed to sense his power, she found him on the ground, barely conscious.
Yui: Kouta! Are you okay?! What happened to you?
Kouta: I trained too hard... but it was worth it.
Yui: That was crazy! You were able to disappear forever. Promise me you won't do that again!
(If a ghost dies, considering they've already died in real life, they disappear forever, unless Adeus or Gares rescue them as Angels or Demons, which technically leaves them completely in control of them, without judgment of their own.)
Kouta: ...It's fine. But let's go home. I need to rest.
Yui: Don't even think about sleeping on that rock again. You're going to rest in a bed.
Too weak to argue, Kouta ended up sleeping at Yui's house. However, upon waking, he felt a distant energy calling him. Without making a sound, he left the house and sped off in search of Haruto.
Suddenly...

Current Powers:
Kōta: 240 (after recovering)
Yui: 102
Haruto: 400
Demons 1 and 2: 150 and 120

Chapter end