"You're alive, kid!" Gu Yan said when he spotted me.

I averted my gaze. "Yeah...just barely. Qing Yue saved me."

"The other two are keeping the monster busy for now, but their mana is running low..." Gu Yuan said. "My own mana is completely out as well..."

I gritted my teeth. "I'll hold the monster off. How long do you need to recharge your mana, senior?"

Gu Yuan looked away in embarrassment. "My mana recharge speed has never been good...it'll take a full day."

A full day...?! That's...way too much, isn't it? But he doesn't seem to be lying, either...oh, wait! Isn't there a Blessing Element spell that restores things to a person...?

"...I see. Qing Yue, use Restituo magic on him."

The senior's eyes widened. "Restituo...I see! That spell family in the Blessing Element!"

Qing Yue nodded, and placed her hands on the senior's back. "Restituo: Mana."

A faint green light appeared from behind the senior, and after several seconds, Qing Yue removed her hands and the senior gazed down at his palms in wonder.

"This is...my mana is fully restored!" he exclaimed in surprise.

"I'm...glad..." Qing Yue murmured, and it was then that I noticed the sweat forming on her forehead.

But it was too late. Qing Yue's consciousness faded away, and she began to fall. I immediately appeared behind her and caught her before she hit the ground.

"Qing Yue! Hey! Wake up!"

She was breathing heavily, sweating harder by the second.

"Big Brother...Xuan Kai..." she whispered quietly.

I pulled her into a tight embrace, and cursed. "Damn it....you idiot...I told you to take a damn break!"

"So...rry..." she murmured, and opened her eyes. "I...wanted to be...useful to you..."

With these words, she faded back into unconsciousness once more.

This was something known as Mana Exhaustion Syndrome - MES. When someone completely runs out of mana, this syndrome occurs. Symptoms are very similar to that of a high fever - sweaty forehead, headache, high body temperature, flushed skin - all of which Qing Yue has right now. Normally, this sickness won't activate unless you completely drained all of your mana, but since most people have common sense and know when to stop, this syndrome doesn't actually occur all that often.

...But when it does, it's very dangerous.

According to what they taught about this during school, MES has the ability to kill someone. Because they are completely out of mana, their Dantians are empty. If one's Dantian is left completely empty for too long, they will become dry, and eventually break. Once the Dantian is shattered, it's only a matter of time before the person dies.

There are only two solutions to MES - one, is by luck, something I'm not a huge fan of. We would have to wait and see if Qing Yue is able to fix this problem herself. The second option is by injecting mana inside of her from the outside - using something like a Restituo spell.

I turned to Gu Yuan. "Senior, hold the monster off a bit. I'll try to cure Qing Yue."

"Cure...? How? You don't have a Blessing Magic affinity, do you?" he questioned.

I averted my gaze. "I can at least give it a shot. Please...don't pry anymore."

Gu Yuan stared at me for a while longer, before finally giving in with a sigh. "I don't know what you're up to, kid, but...I owe that girl a favor. Don't let her die, yeah?"

I nodded. "I won't."

After hearing my firm words of confirmation, Gu Yuan headed off into battle, joining Ke Tian and Ye Xiao Xing. I immediately turned back to Qing Yue, and placed my hand on her chest.

Restituo: Mana.

Since no one was within earshot, I could safely cast a spell without saying the incantation out loud. A faint red light appeared from beneath my palm, and I continued pouring mana into the spell.

I've never used this spell before, but...Qing Yue's taught me it. Please work...

Then, after a good ten whole seconds, Qing Yue suddenly started coughing, and I stopped my spell.

"Qing Yue! Are you okay?!" I grasped her shoulders tightly and asked in worry.

"Huh...? Big Brother Xuan Kai...?" she murmured.

"Yeah. I'm here. How are you feeling?"

"My headache...it's gone!" Qing Yue exclaimed, before diving into my arms happily. "Big Brother Xuan Kai...thank you...you actually learned the spell I taught you only once..."

I sighed. "It was just a stroke of luck that it worked. And you, my cute little idiot, should never do something like overexert yourself to this extent ever again."

I karate chopped her head lightly, and she made a fake pained expression with her tongue out. "Ehehe, I got it, Big Brother Xuan Kai!"

I then stood back up and turned to the monster, as well as my teammates desperately battling it. "Now then...how are we going to deal with this thing? It would be great if we had some more assistance, but..."

"Did someone call for assistance?" a familiar voice cut in from nowhere.

I spun around immediately, to see Yu An Yan carrying her sister while levitating in mid-air. She gently landed on the ground and let Yu An Xue down.

"An Yan! An Xue!" Qing Yue yelled happily.

"Qing Yue!" the two sisters quickly ran closer and the three of them embraced one another in one giant hug.

"You two...you're safe?" I murmured in surprise.

"Well, yeah. We aren't going to just let you get away after those harsh things you send to us," Yu An Yan replied.

"Mm...agreed," Yu An Xue added.

I averted my gaze. "Er...a-ahem, that aside, how did you even find me?"

"Are you really surprised? With all the noise you guys made over here?" Yu An Yan said with a shrug. "Even if I wanted to ignore it, I just couldn't."

I laughed awkwardly. "Yeah...about that. You two have those weapons, don't you? I bet those can do actual damage to this monster."

The girls looked at where I was pointing, and sank into thought. "Huh...I've never seen a monster like that. Is it some sort of mutation...?"

I shook my head. "I don't know. But for now, we need to take it out. And quick."

"Kid!" Gu Yuan called out in the midst of battle. "We can't hold out much longer here!"

I looked at the two Yu sisters. "I'm under a cover identity here, so I can only use one element. Besides, magic doesn't do anything to it anyways. And my actual weapon...it's unable to hurt it at all."

I glanced down at the obsidian sword in my hand, as the Yu sisters exchanged looks and sighed together.

"...Why do you keep getting yourself caught in these situations?" Yu An Yan muttered.

"Er..." I wanted to say 'I joined to look for you', but that would be to embarrassing so I didn't end up saying anything.

"Ah, whatever. An Xue, let's do this, yeah?"

Yu An Xue nodded in response to her sister's words. "Mm. We'll...show you...we aren't weak."

With this, the two of them materialized their weapons - one a flaming axe, the other a frozen sword. They rushed towards the monster in perfect sync - the way they moved in time with the other without any words was quite the sight to behold. I felt like I was witnessing the greatest teamwork in the world right now. Gu Yuan, Ke Tian, and Ye Xiao Xing were surprised by the sudden help, but they immediately moved to make way for the two sisters.

Once the two of them were within range of the monster, Yu An Yan wordlessly held her axe in front of her as Yu An Xue jumped on it. Yu An Yan then launched her sister off the axe, and Yu An Xue, making use of this momentum, went straight for the monster's eye. Blinding it first was the best course of action here, and as expected of one of the Six Divine Weapons, Frozen Fear, Yu An Xue's weapon cleanly cut the monster's single, massive eye, and did a backflip by using the monster's shoulder as a foothold.

As soon she even landed back on the ground, Yu An Yan was already on the move. Taking advantage of the blinded monster, she spun her flaming axe around for momentum, and then dashed in between the monster's legs. Then, like a sharp and deadly spinning top, her axe severed the monster's two feet with ease, and she got out of there immediately right before the monster collapsed onto the ground.

However, it still wasn't dead. The two sisters met up, leapt into the air, and pointed their weapons directly at the creature's heart.

"Hyahh!" they yelled together, and soared towards their target.

Their attack hit its mark, and after one final bloodcurdling scream of agony, the monster fell limp, never to move again. The Yu sisters pulled their weapons out of the monster's chest, and casually dematerialized them.

Triumphantly, they returned to me as Gu Yuan, Ke Tian, and Ye Xiao Xing watched on in wonder. Two mere high school girls had just defeated a monstrous opponent even the three of them together couldn't leave a scratch on. I was also shocked by how strong they have gotten.

The strength they showed just now - it wasn't just the powerful weapons they had. Yes, the Divine Weapons played a role, but their seamless teamwork was something no object could replace.

"Monster, dead. How do you like that?" Yu An Yan said with a victorious grin.

I chuckled. "Not bad, I suppose. But...you still won't be able to defeat me."

Yu An Xue was the one to reply this time. "That...may be so, but...we will continue getting...stronger. One day...we will defeat you."

I cackled evilly. "Kuku...then I'll wait for that day."

The speed at which they became this strong...it's truly terrifying. Was this the power...of sisters? Kukuku...I really am looking forward to see just how strong they can become in the future.

...But of course, I will always be one step ahead of them.