When Sayomi opened her eyes, she immediately shut them again. Daylight in the Demon Plane was blinding compared to the Void. After letting her eyes adjust, she looked around and clenched her fists angrily.

Hiei was to her left. He was on his knees, glaring up at Sensui. He looked as beaten and tired as he did in her mind. Beside him, Kurama was laying on his side, propped up on a bruised arm. Blood trailed from his mouth, but his eyes didn't stray from Sensui. Next to him, Kawabara was splayed out on his back. He struggled to keep one eye glaring at the rogue detective.

Surrounded by smoking craters, Sensui looked down at them without a single scratch or bruise on his person. "This reminds me of an RPG video game, where I max out my character before challenging the last boss. He can't hurt me, but as he has 10,000 HP and I can only manage to shave off 100 HP at a time, it takes a while to whittle that down and take him out. After that... I feel both a strange pleasure and an emptiness. It's the way I feel now. I'm sorry I made you suffer."

Hiei smirked and sat down with an arm resting over a raised knee. "Never mind that. You were just lucky."

"And stronger than we are at this moment. But that's all it takes to win." Kurama smirked, dragging himself to sit up.

"If Yusuke were still here, we might have managed a better challenge. That idiot..." Sayomi smirked bitterly. "Then maybe you would've realized who you were really up against."

Sensui listened patiently until they finished. Then he lifted his hand and began to focus his aura. "I'll finish it, then." Before he could attack, he snapped his attention to the distant light that was the tunnel to the Human World.

Sayomi followed his gaze, then froze. Her eyes widened and her jaw hung open in disbelief. I recognize this aura, but... it's different...

Hiei and Kurama stared in awe as a blue bird steadily flew closer towards them. Kuwabara sat up straight, forgetting his wounds and fatigue. Sayomi could feel a smile stretch across her face as tears started building in her eyes.

As the bird landed in front of them, a living ghost hopped down with Koenma.

"Is it really...?" Sayomi couldn't speak any louder than a whisper.

"Yu...suke?" Hiei asked, unable to believe his own eyes.

"I don't..." Kurama couldn't, either.

Kuwabara could only stare with wide eyes, stunned to silence.

"Sorry I'm late, guys! But it looks like I'm just in time!" Yusuke walked up to his beaten friends and stared at them with his hands on his hips. "Did you really think I'd leave you poor saps to finish what I started?"

"But..." Kuwabara reeled. "Your heart! It stopped! And that aura of yours... It's demonic!"

"Yeah, it is," Yusuke confirmed. He tapped his chest and blinked. "And my heart did stop. In fact, it still is stopped. Weird, huh?"

"Heh..."

"Heh heh..."

"Pfft..."

Yusuke and Kuwabara blinked as Kurama, Hiei, and Sayomi burst into laughter.

"Heh heh... Ha ha!"

"Ha ha ha ha!"

"Ah ha ha ha!"

"Heh heh..." Yusuke grinned.

Kuwabara stared at them like they had all lost their minds.

Calming down to a quiet chuckle, Kurama said, "Your 'core' now beats, instead of your heart. A demon heart."

"So there's demon in you." Hiei smirked. "Guess I'll never figure you out."

"I'm pretty puzzled about it myself, too," Yusuke confessed. "I don't feel any different..."

"You'll get used to it." Sayomi smirked. "Gotta say, it's about time."

"Wait!" Yusuke turned to Sayomi and blinked. "You knew this would happen?!"

Sayomi shrugged. "I didn't know that you apparently had to die, but... I suspected it. Really, I wasn't 100% sure you were the one I was looking for, but you seemed like the best bet."

"We might have to talk later," Yusuke said.

"I agree."

Sayomi froze when she heard Koenma speak up behind them. When she turned to look, he was staring at her. He doesn't look angry... but he doesn't look happy either...

"Hey, Sensui!" Yusuke turned to his predecessor. "Sorry to keep you waiting! Shall we pick up where we left off?!"

"Hold on there, po'dner. I'd like to take him on first," Hiei said. His aura flared around him as he got to his feet.

"Same here," Kurama agreed. Despite his wounds, the Fox Demon stood up, ready for another round.

"Me too!" Sayomi jumped to her feet eagerly. "Let me fight him!"

"Geez, what went on while I was dead?" Yusuke asked. "You all seem sharper, stronger...!"

"Heh... Heh heh..." Kuwabara jumped to his feet and grinned. "Wait, I'll go first! I can beat him! I know I can!"

"You're delusional," Hiei muttered dryly.

"Stop saying that, you miserable runt!" Kuwabara yelled.

"Just stating a fact, moron," Hiei said.

"Why don't you come say that to my face, shrimp!"

Hiei looked straight at Kuwabara and said, "Moron!"

Kuwabara growled and swung a punch at Hiei. Hiei simply took a quick step to the side, letting Kuwabara fall flat on his face. Sayomi and Yusuke laughed while Kurama smiled and chuckled. Meanwhile, Koenma stared solemnly at Sensui. Sensui only glared as he observed his old boss' new team.

Once his laughter was out of his system, Yusuke fixed his own glare on Sensui. Sayomi and the boys quickly followed his example. Sensui answered by emitting his aura.

As if in response, Yusuke's new demonic aura began to swirl around him. "I know how you guys feel, but I really must ask you to let me..." He turned to smirk at his friends with a glint in his eye. "Go first."

Kuwabara swallowed a nervous lump in his throat as he saw Yusuke's scary face. Hiei aimed his finger at Yusuke and said, "Very well. But rest assured, I'll catch up soon... to you and him."

"Just don't die again, please," Sayomi added in. "I think the one time is all I can handle for one fight."

Yusuke smirked and turned to approach Sensui. Sensui, in turn, walked towards Yusuke. They circled each other and took in a deep breath. Then, they both leapt into the sky.

They met in midair, throwing a barrage of punches that clashed with the other's punch. The mere force of their attacks was enough to make a large sphere of aura around them.

Sayomi and the others had to brace themselves against the strong gale that blew around them. Rocks tore out of the ground and flew through the air as their power made a large crater.

When Sensui punched Yusuke in the face, the young detective landed on a large boulder in a crouch. Sensui closed in and punched down, smashing the large rock into pebbles. Yusuke jumped out of the way and fired off a large bullet of aura.

Sayomi and the boys watched the blast with stunned faces. That's huge!

Then the blast blew just past Sensui, who looked down at his armor with wide eyes.

He just barely grazed him?! With a blast that big?! Sayomi couldn't believe her eyes.

"Huh?!" Yusuke blinked. "I missed? No way!" He looked down at his trigger finger in confusion. "I don't get it..."

"I'm not sure I do, either," Kurama confessed.

"His senses haven't yet caught up to his new level of power. Knowing him, though, he'll adjust pretty quickly," Hiei concluded.

"He's gonna have to. Otherwise he won't stand a chance," Sayomi said.

"Don't waste your shots, Urameshi!" Kuwabara warned. "You fired one off before you went in the cave, y'know!"

"Ah..." Yusuke blinked. "That's right. And I fired a Shotgun, too. Hmm..." He looked down at his hand and saw one glowing fingertip. "One more. Well..." He smirked. "I'll save it for the right moment."

"Hrrrn!" Sensui charged his aura, catching Yusuke's attention. The armor dissolved from his body and his power only continued to grow.

"He shed his armor!" Kuwabara reeled. "But his aura... it increased!"

"He's switching to attack mode!" Koenma realized.

"Are you saying he wasn't already in attack mode?" Sayomi asked. "You gotta be kidding me..."

Yusuke turned back to them and said, "Pu, round everyone up and clear the deck. This could get a bit messy."

As Sensui's armor reassembled itself around his body, Sayomi and the others latched onto the large bird. Kuwabara and Koenma managed to climb up to the beast's back while Sayomi and Hiei hung from each of his legs. Kurama used a seed to open those large leaf-like wings from before. As soon as they lifted off the ground, Sensui moved.

"Shah!" Sensui dashed and punched Yusuke in the face before he could block. Yusuke was sent skidding back across the floor and Sensui charged to punch the boy up into the air. "Hah!"

The attack shattered a large portion of the plateau into large boulders that fell to the forest below. Sayomi felt her mouth hang open as she stared at the scene. So this is what it's like for two S Class power levels to clash...

Yusuke jumped up and used the falling rocks to spring towards Sensui. He assaulted Sensui with another flurry of punches. Sensui blocked each one until he used an opening to punch Yusuke in the face. He used the moment to turn the tables and attack Yusuke with his own punches.

"Ack!" Yusuke was forced to block until Sensui punched him through more falling rocks. Yusuke used his aura and landed on another rock. He smirked up at Sensui and licked his lip.

As Hiei pulled Sayomi up to Pu's back, she saw the plateau had become two pillars surrounded by a large pile of sharp rocks.

"Holy cow!" Kuwabara gasped. "In just a few seconds, they blew that huge rock away!"

"This is insane... If they had fought like this in the Human World, there wouldn't be anything left!" Sayomi tried to imagine the destruction that would ensue from their fight. Maybe it's a good thing he didn't become a demon in the Human World.

From his pillar, Yusuke smiled and said, "Hey, let's move to another arena. Someplace with more room to maneuver."

Sensui smirked. "I'd like that."

Yusuke pointed off to the distance. "You see that high pillar over there? It's all rocks and sand beyond that."

"You've been there before?" Sensui asked.

Yusuke smirked. "I think my ancestor has. Let's go!"

Sayomi gasped when she saw them take off. They're so fast!

"Where'd they go?!" Kuwabara asked frantically.

"Thataway!" Koenma pointed out. They were only two small specks in the distance.

As they closed in on the pillar, Yusuke convulsed as he felt a strange sensation in his body. "Huh?" He looked down at his chest curiously. "Hmph! Fine..."

As soon as they reached the pillar, they crashed through it and immediately started fighting.

"Wow!" Kuwabara watched in shock. "They didn't wait to get started!"

Yusuke and Sensui sprang from the falling pillar. Yusuke bounced across the sands while Sensui flew in the sky. They met with a clash of powered punches until they ended up in a stalemate. Their hands clasped together, both trying to overpower the other.

"Gnrr!"

"Hrrn!"

Their power flared around them as dust storms. Twisters formed around them while sand erupted from beneath their feet in a large ring.

"An aura cyclone!" Kurama gasped.

"Stay back, Pu," Koenma instructed. "Let's not become collateral damage."

Sensui punched Yusuke in the face, sending him bouncing across the desert.

As the storms died down and the sands settled, Sensui turned and said, "I know you're behind me. Don't being sneaky if you can't hide your aura."

"Heh..." Yusuke popped out from under the sand and grinned sheepishly. "Guess you're right. It's like riding a bucking bronco... I can't rein it in yet." He smirked. "But I'm getting the hang of it."

Sensui returned his smirk.

"Hey, what's that smile about?" Yusuke asked. "Still got something up your sleeve, eh?"

"Not exactly." Sensui's expression darkened. "Hardly worth your notice."

"Tell me," Yusuke demanded.

"No, not yet."

"Feh!" Yusuke pointed an accusing finger at Sensui. "You're trying to bluff me!"

"Heh heh... Perhaps," Sensui allowed.

"Whaddaya think, Hiei...?" Kuwabara slid a worried glance at the demon. He paled when he saw him sleeping in Sayomi's arms. "Uh..."

"Shut up," Sayomi growled defensively. "He wore himself out summoning the Black Dragon twice!"

Kurama watched the battle below and said, "Yusuke may not yet have full use of his powers, so Sensui may still have an edge..."

"Okay, whatever. Ready for round two?" Yusuke challenged. "Rrrgh..."

Sensui only smirked at the young boy.

Then Yusuke convulsed.

Sensui scowled in confusion.

Yusuke glanced down at his body. "Huh? What now?" He hunched over as he tried to speak. "I... I'm..."

Sensui watched, curious about what was happening.

"Yusuke...?" Sayomi watched in worry. What's happening now?

Then Yusuke stood straight up as his aura erupted from his body in massive waves. Strange tattoos started appearing on his body and his hair quickly grew down to his knees. The transformation ignited more cyclones and sand storms.

Sayomi's eyes widened as she realized what was happening. This is what he was talking about...!

Sayomi remembered her last meeting with the Old Man.

"Yes, my lord. May I inquire what it is I should be looking for in your heir? What traits he might possess that might single him out from all the others?"

"Well, I don't know." She could hear the amusement in his tone. He was doing this on purpose. "It's been hundreds of years by now. I suppose a good start would be to keep an eye open for anyone with unusual fighting prowess. In fact, I'd imagine he might even enjoy a good fight." His tone became hopeful and expectant. He was looking forward to the meeting.

Sayomi nodded and asked, "Is there anything else I need to know? Will there be anyone to act as an escort during my mission or am I going alone?"

"This will be a solo mission. Anyone I send with you would probably draw too much attention in these more modern times." The ruler leaned back into his throne, relaxing now that the important topic had passed.

"How will I know when he's ready?" Sayomi persisted. She might as well try to get as much information as she could before she left.

"You'll know." He rested his chin on the back of his right hand, his arm propped on the armrest of the throne. "When he's ready, he will bear the markings of his ancestors and his power will be unmistakable."

Sayomi snapped back to attention when she heard Kuwabara yell, "What the Blazes is going on?! Is that... Urameshi?!"

When Yusuke emerged from the storm, his whole demeanor seemed changed. His aura was completely demonic and he focused only on Sensui.

Sensui watched in awe as he realized what he was fighting. "Brilliant."

"Grarr!" Yusuke charged and punched Sensui in the face. He immediately chased after Sensui's body and smashed him down into the ground.

"Guh!" Sensui coughed up blood and was kicked up into the air.

Yusuke sprang after him and grabbed him by the shoulder. He punched Sensui in the stomach several times, giving him no chance to fight back. The intensity of the attack produced a large dome of demonic aura.

"Toast my toenails!" Kuwabara stared down at the fight with clenched teeth. "Is that... Is that really Urameshi...?"

"I can't say what triggered it, but it seems he's awakened... completely." Kurama stared down, ignoring the blood running down his head. "I never realized he had so much untapped power. His ancestor must've been a Battle God. Sensui's only human. He's no match for it."

Sayomi bit her lip as she silently watched the battle. You're not far off from the truth, Kurama. I just wish it hadn't happened so soon...

As the dust cleared, Yusuke was holding Sensui off his feet by the throat. He squeezed, cutting off Sensui's air. Then he smirked and said, "And now... the big finish!"

Yusuke flung Sensui up through the air and took aim. His sinister smirk flickered to a surprised stare as he fired off his last bullet. "Dodge it, Sensui! Dodge it!"

"What?!" Sayomi gasped at Yusuke's desperate cry.

As Yusuke yelled, Sensui turned to smile at him. Then the blast hit him directly, shattering his armor and sending him crashing through the forest in the distance.

"Sensui!" Yusuke chased after him, using his demonic aura to increase his speed. "You idiot!"

"Why's he so worked up?" Kuwabara asked. "He won! That Uber Reigun Blast hit Sensui dead center!"

"He's back to normal again, but... why did he change like that?" Sayomi tried to figure out Yusuke's flipped personality. He looked like he was enjoying the fight until the end, then he switched off to not wanting to win...?

"Get going, Pu! Hurry!" Koenma urged the beast forward.

"What's going on?!" Kuwabara asked.

Pu flew after Yusuke, following a path of destruction. Sayomi swallowed a large lump in her throat as she stared down. "Yusuke... managed to do this? The Old man was right. It is unmistakable..."

"Wow, that gash..." Kuwabara was just as impressed. "It goes all the way to the horizon! How could anyone have survived that?"

Koenma narrowed his eyes as he scanned for the two fighters. "There!" He guided Pu to the end of the long path where Yusuke kneeled over Sensui, clenching his torn armor to shake him awake. As they neared the ground, Kuwabara jumped off Pu's back to run up to them.

"Sensui, wake up!" Yusuke yelled as loud as he could. "Open your eyes! C'mon! This isn't how it's supposed to go!"

"What're you talking about, Urameshi?" Kuwabara asked. "Don't you see? You've won! Pluh!"

Yusuke punched Kuwabara into the air. "That wasn't me! I mean it was, but it wasn't! I wasn't there when I fired that blast! I only saw it fly!"

"Yusuke?" Sayomi laid Hiei on Pu's back, then jumped off to run up to him.

"Koff..."

"Sensui!" Yusuke looked down at the former detective as Koenma and the others rushed forward. "Kurama, what about your herbs?! Don't you have any that'll heal him?!"

"His injuries are too... fatal. I can only help ease his pain," Kurama said regretfully.

"What about you, Sai?! Can't you patch him up?!" Yusuke turned to her with a glare.

Sayomi heaved a deep sigh and said, "Sorry, Yusuke. I used a lot of aura just fighting him. I can't even patch myself up at this point." She stared down at her clenched fists. Her markings were just as they were in the Void. "If I try anything now, I might not last."

"There's no need."

Everyone jumped at the sudden familiar voice. Sayomi looked around until she saw hole opening in front of them to reveal a familiar demon.

"Itsuki?!" Yusuke gasped.

Itsuki looked at them with one eye. A long scar dragged down across his other eye, where Kuwabara's sword cut through his creature. He looked tired and weak. "His time has come."

"Whaddaya mean?" Yusuke asked. "Stay outta this! This doesn't count! Blast it, he owes me a rematch!"

"He only had two weeks left, anyway," Itsuki said.

"What...?" Yusuke stared at him dumbfounded and got to his feet. "Two weeks? To live?"

"Yes," Itsuki said. "He suffers from Aggressive Malignant Tumors. Dr. Kamiya diagnosed him. A normal human would've died of the condition long ago."

Yusuke kneeled down to ask Sensui. "Is this true?"

Sensui opened his eyes. It was the most he could do. "Yes, but... No excuse. Your power was... superior."

"No!" Yusuke shouted. "That wasn't my power! I was out! I wasn't here!"

"Your subconscious was here," Sensui explained. "And it could control that power quite well. It was you... no other... who unleashed it."

"That's not good enough!" Yusuke argued. "You know that! You still have two weeks! You can rally! Take painkillers if you have to!"

"Yeesh!" Kuwabara cringed.

"Can't you do something, Koenma?" Yusuke turned to the young prince. "You're so all-powerful, ain'tcha?!"

Koenma looked down at Sensui and said, "Perhaps if I still had the aura stored in the Seal Ring, but I don't. Shinobu saw to that, I'm afraid." He turned to Yusuke. "Even so, I'm not sure it would be enough, or in time."

Yusuke blinked at Koenma, confused.

"You... saved Amanuma, then." Everyone looked back down at Sensui. "Heh... Just as I'd planned. Your Seal Ring... I had to deal with that, get you... to waste your aura... before you used the ring..."

"But why?" Koenma asked. "Why did you want the portal?"

Sensui took in a deep breath as he stared up at the sky. "I wanted... to reach the Demon Plane... that's all. When I was a child, I wondered about many things. 'Why are there creatures only I can see? Why do they hate me? Why are they always trying to kill me?' I learned to fight them, but I... never got answers to those questions.

"'I must be a chosen warrior of justice. They must be evil forces out to harm mankind.' My simplistic dualism... Slaughtering those creatures... I got used to the carnage... I believed... there was good and evil... That wars were fought between the evil... and the just. Such thinking was easy..."

Sensui smiled. "But it was... wrong. Humans know nothing of justice. I hated that failing... And that I shared in it. I yearned for a... heritage... from the Demon Plane. That yearning drew me, called me... commanded me. When I found out I had little time left... I felt a strange liberation. The barrier tunnel was... my little gift to the Demonic Realm. All I wanted was to die here. Urameshi..."

Yusuke stared down at Sensui, waiting to hear what he had to say.

"You truly reveled in our fight. So did I... If only for a moment. Thank you." Sensui's eyes glazed over as he took in his last breath. "Next time... Let me be born... a demon..." His head rolled to the side as he passed away.

Sayomi and the others could only stare down at Sensui's body in silence. Then Koenma stepped forward. "Shinobu..."

"Stay back." Itsuki glared at Koenma. "It's over, isn't it? So leave him, let him rest..."

Itsuki walked towards Sensui and lifted his body, holding his arm over his shoulders and supporting his waist. Itsuki summoned his floating eyeball-covered arms to close his portal around them.

"Koenma," Itsuki said sternly. "He had no wish to go to the Underworld. He cared nothing for your values. His soul is not yours to claim. We'll deal with eternity our way, just the two of us. This business of living has grown tiresome. Go!" He smiled as he and Sensui disappeared. "Find another enemy in your eternal struggle."

Once they were gone, Yusuke grinded his teeth. "Geez... It's like my opponent just... ran away."

"Same result, anyway," Kurama agreed. "In the end, he achieved his goal."

"By the way, Urameshi..." Kuwabara said. "Do you feel any different?"

"Different?" Yusuke blinked. "Well, my head seems heavier..."

Sayomi smirked as she snuck up behind Yusuke and pulled on his hair. "You mean this?"

"Yipes!" Yusuke yelled in pain as he rubbed his head. "This hair! And my skin—!" He looked down at his arms that were covered in strange markings. He scratched his head and back as the strands made him itch. "Sheesh! I guess... I've really become a demon."

"Your ancestor was Class-S, I think," Kurama said. "And there's no reason to suppose he's deceased."

Sayomi looked down at the ground shamefully. I know I need to tell him, but...

"Ah! Good point!" Yusuke glared at his clenched fist. "He's the one who delivered the final blow!"

"Come again?" Kurama asked.

"Well, y'see..." Yusuke explained what happened before he lost blacking out.

"A voice?" Kurama asked curiously, crossing his arms.

Sayomi's eyes widened as Yusuke said, "In my mind, before I lost consciousness. I'd fired the Reigun before I was aware of doing it. But at the moment of firing..." Yusuke glared at the forest. "I knew a power an order of magnitude beyond mine had done it. Someone else's power, if you get my drift."

"Hold on a sec!" Kuwabara yelled. "When you arrived on the Demon Plane, you were already as powerful as Sensui! And you still are!"

"Yes, I know," Yusuke said. "But in that moment I was more."

"Y'mean, more powerful than... yourself?!" Kuwabara asked.

"Yeah..." Yusuke nodded.

Kuwabara's complexion paled. "So this demon ancestor of yours... is in some totally out-there class?!"

"By Underworld standards, yes," Kurama answered. "Class S is really a kind of catchall category. It's used for demonic variations that lie outside of the types the Underworld has commonly encountered. The deeper you go into the endless depths of the Demon Plane, the more variations you find, and the less you know about them."

"Heh heh... Okay, fine. Can I go now?" Kuwabara asked nervously.

"All right..." Yusuke pumped his fists. "I'm going to go find this guy!"

"Huh?" Kuwabara did a double-take.

Sayomi stared at Yusuke, unable to speak up.

"Are you nuts?!" Kuwabara reeled. "Let's just get outta here!"

"No!" Yusuke punched his open palm. "He interfered in my fight, and nobody gets away with that!"

"Yusuke..."

Yusuke turned to Koenma curiously.

Keeping a stern face, Koenma said, "I'm not sure you fully grasp the situation. Even now, the Defense Squad is closing the portal. They should be done in about two days. Once it's closed, that's it. You'll have no way back to the Human World. If you want to spend your life fighting, the Demon Plane is the perfect place for it. You have 40 hours to decide."

Sayomi watched as Yusuke absorbed Koenma's words. She clenched her fists as she tried not to influence his choice. If he wants to stay, I'll tell him where he can find the old man. But if he wants to go back, I won't stop him... I know it's selfish, but... I don't want this to end so soon...