The World's most Overpowered Side-Character

The day had quickly become overcast with the threat of rainfall, and after another hour of travel toward the border, the general who was ahead of the march raised his right hand in a fist, causing several soldiers to pull out horns and blow them, creating a faint hum through the air that stimulated mana in the atmosphere; it was a call to action.

"General!" Arla and Idria from his captains approached first, but quickly saw the reason for his alertness.

"Demons... This far in?" Arla asked surprised, making sure to not shift and wake Sol who still clung to her and slumbered peacefully.

"I thought the day was going to go by uneventfully again until we reached the borders of Argom, but this is a concerning development." General Grim stood with his sword drawn staring from the top of the hill at a valley full of demonic beasts and corrupted monsters.

"We crossed this valley just days ago, how could they have advanced toward Argom this quickly?" Idria commented, staring at the monsters, she could even identify several corrupted humans and elves in the mix. "May your souls rest in eternal peace."

"Mages, at the ready." Arla raised her staff, increasing the potency of her mana as she focused it all into a great blue ball before her, waking Sol who had still been soundly asleep on her back.

"I won't hinder you any further," Sol quickly hopped off her horse, standing on his own and staring down at the demons and monsters but when he did his eyes slightly widened, and he sucked in a breath.

"They're the same..." Sol almost summoned a weapon upon seeing them, the same creatures he had fought for ten years on Atla were the same creatures he was seeing, not just him, but Ikaris seemed disturbed too as she stared at them when the army converged at the ready.

She had a suspocion that such was the case, but this confirmed it, these demons, wherever they were coming from, they seemed to be a part of the same race, an entirely separate reality where only they existed.

This made her question wether she was going to be able to attack and fight them effectively, so as a test she fired off a preemptive bolt of her gathered Arkadian mana, and then another bolt of her pure divine mana.

"Fuck," Sol stared in shock when her divine mana was harmlessly negated by the creatures, while her Arkadian mana collided and exploded in a plume of sparks that pierced and killed scores in one shot.

"This changes everything!" He seethed and grit his teeth as they slowly sharpened. "How, why?" Sol asked, watching the beasts and demons make their way up the hill after Arla and the mage corps erected a barrier on either side of them creating a kill-passage to prevent them from getting surrounded.

"Mages retreat to the back and prepare your support spells!" Arla took to the air, accompanied by Dina and several other skilled mages while the others quickly withdrew behind Kris, Bruce and the rest of the tanker frontliners.

"Master..." Ikaris sensed Sol's power rising along with his frustration and rage.

"This again," Sol stood on his horse with his eyes glowing menacingly as he summoned a sword, but then a window popped up before him.

[True Goddess Ikaris implores you to keep your word and not raise a hand against the demon horde unless completely necessary]

"What?" Sol looked around and found Ikaris ascending with her white wings.

"I may not be able to harm them with my divine magic," Ikaris stated.

"However, I no longer possess just divine mana, the whole time I have been here I have been honing my Arkadian mana and gaining strength in case this happened, while it is nothing close to Master's own power or my divine power, I am still the strongest amongst the heroes!" Ikaris created a sword out of mana and then solidified it until it became a physical object.

"This changes nothing!" She descended, using her divinity for mobility to spare her mana for fighting.

"I can finally kill you invasive bastards, I'll relish in this opportunity!" Ikaris's expression went dark for a moment as she descended like a comet and tore through the demons sending several hundred of them flying into the barrier as nothing more than chunks of meat while she ascended the hills again and landed at the front of the charge.

"This will be my revenge!" Ikaris aimed her sword to the skies. "Watch closely you useless gods, I'm doing what none of you have the power to do!" Ikaris suppressed her wings and charged ahead of the army as both sides clashed.

"I can't tell if she's enjoying this or not, but she's right." Sol directed his horse to the highest point on the battlefield and watched keenly as her and the other heroes fought.

"If it's like this, then I think I'll end up fighting that Demon God after all, regardless of what I feel or want to feel," Sol narrowed his eyes.

[The goddess of war is in shock]

"Huh?"

[The pantheon is in shock at True Goddess Ikaris's ability to kill the demons]

[The god of bets has placed a bet]

"Ah, the gods of Arkadia are incapable of using anything other than their own divine mana, so you can't save your own world from this invasion," Sol sighed pushing the windows out of his way.

"Usually I'd have something to say about it or poke fun at you somehow, but if Ikaris can't utilize her divine magic against them either then it means the demon race is utilizing a special type of magic or bodily constitution that is immune to divine magic across all dimensions," Sol explained to those listening as his mood grew darker. "Just how many worlds have they destroyed this way?"

[This is a confession that they have already encountered these beings elsewhere, but their earth has never been invaded, so my guess was right, after all.] Dr'ul stared at Ikaris intently, she remembered trying as well when the demon god first appeared.

To see a foreign god protecting her home when she could not, made her doubt herself and her powers, it filled her with bitterness at how powerless she was as the goddess of war.

[Impale!] Usami bent beneath the swing of a large demonkin with eyes in its arms and stabbed it in the stomach. [EXPANSION]

Her spear vibrated with waves of golden mana and then exploded in length, impaling several dozen demons and beasts in an instant and creating a kebab out of them.

"Han!" Bruce used the basic technique [slash] to cleave his way through several and then threw his shield on his back and took a knee, blocking a bolt of dark mana with his broadsword while Han used his shield as a springboard to gain height above the demons.

Airborne, Han summoned a second sword midair and kicked it by the handle, saving several soldiers when a behemoth emerged from the ground before channeling mana into his main sword. "I'll vapourise every last one of you!" Han shouted in his descent.

[Unique skill: Creation, has been activated]

[Sword Dance: form 1]

"Thunderbird!" Han landed in the midst of the demons, slamming his sword in the ground and manifesting a great bird of yellow lightning that made a frontal horizontal rip across the demon hordes creating an even larger area of effect explosion than Ikaris had caused with her mana sword earlier.

"He-he-he-he-he~" Ikaris held a sly grin on her face as she grabbed a demon and used it as a shield and hammer against several of its fellow kin. "I see, this is it," She released the dead creature and dodged another one's attack stabbing it through the head. "Haha I see -I see!"

[×300 Low-level Demonkin killed. +12,000xp]

[Level: 145 (+5)]

[You levelled up, mana has been restored]

"This is what master meant by a mine of experience!"

"Ah, so she is enjoying it," Sol shut his eyes and folded his arms, relaxing on his horse.

[Healing Arrow]

Idria stood on another high perch next to Eris who had her AOE healing spell at full throttle.

A white arrow made of mana appeared in Idria's grasp, and then a long bow made of mana formed as well, and she aimed it to the frontliners and fired it.

"What happens if that arrow hits and heals the enemy?" Eris asked when the fast projectile flew over everyone's head, but blinked several times in confusion when the arrow changed directions and dodged several enemies and crashed harmlessly into Kris's back, healing his injury.

"I have honed this skill for years, focus on your tasks, Eris." Idria scolded her, and a trickle of sweat rolled down Eris's cheek as she held out her hands and increased the potency of [heal]. The battlefield was large, so she couldn't cover everything especially at the cost of healing the enemies, so their wounded allies had to retreat into the healing area.

"Dina, focus on the back of the horde, thin them out and push them inside of the barrier!" Arla started closing the front of the [Great barrier] she had made when the last of the horde started entering. And seeing this, General Grim ordered an immediate retreat.

"You mean...?" Dina looked at Arla surprised and the half-elf nodded.

"Yes, we go with that attack."

"Right!" Dina pressed her hand on her breasts.

[Activating weight manipulation]

[Lightweight Activated]

[Activating thrust]

[Activating propulsion]

[Wind manipulation]

She cast five different spells simultaneously.

"I'm off then!" Dina took to the skies like a plane, causing Sol to peer an eye open for what was about to be the climax of the battle that barely lasted an hour.

Approaching the rear of the small horde, Dina summoned her staff again and waved it several times gathering mana before pointing it toward the edges of the scattered and chaotic enemy formation.

[Combination magic]

The cloudy skies lit up with hundreds of crackling balls of golden mana encompassing the entire back of the demon horde while the last soldier made their way out of the front of the barrier and Arla shut it.

"Dina's eyes widened as she pointed to the horde, turning to a bright pink hue as the balls of mana began descending with tails made of electricity and mana like falling stars.

"Origin explosions!"