[Edit] Don't worry gentlemen, we have the technology.
Makai, GensokyoThat idiot! Yuuka thought as she saw John shooting at Shinki. All of the bullets proved to be ineffective.
"Don't you understand?" Yuuka shouted at her Character comrades. "Shinki is the goddess of this realm! She can kill you within seconds! Just stay far back and don't do anything!"
As Yuuka was shouting at John, the valley disintegrated completely, forcing Yuuka to take flight.
"Come to think of it, we never got to decide who was the stronger one." Shinki snarled.
"Well, let's determine that right now." Yuuka smirked, her sadistic needs growing. Flowery bullets, too many to even be able to estimate, started appearing from behind her.
"Kami Sign - Fallen God!"
"Bloom Sign - Rafflesia!"
When an ordinary human gets lucky enough to observe two Youkais' spell card duel, all and everything that the human considered beautiful pales in comparison to the wonderous art that the danmaku makes. Stronger the youkais, stronger and more splendid their danmakus, cacophony of bright and vivid colors mixed together into deadly concoction of patterns, too deadly and too gorgeous for words.
The barrage that continued for 5 minutes ended up with neither of the Youkai taking any hits. They both grinned as they prepared their second card.
"Kami Sign - Wings of Osiris!" Gusts of deadly wind blows toward Yuuka.
"Bloom Sign - Angela's Trumpet - Lunatic!" Trumpet-like bullets envelop around Yuuka, defending her from the wind bullets.
"Kami Sign - Endless Death!" Shinki fires a barrage of rapid fire blue bullets. Yuuka flys around to dodge, but the bullets are homing.
"Bloom Sign - Ghost Orchid!" Yuuka fires an equal amount of Orchid bullets that explode on contact with the blue bullets.
"This isn't taking anywhere." Shinki growled. She never anticipated Yuuka to be this stronger.
"Indeed." Yuuka smiled. She was out of breath, but she could manage. "Shall we continue?"
"Of course." Shinki frowned, and lunged towards Yuuka. "Kami Sign - Thanatos!"
Shinki's wings turned into levitating swords as they danced around Shinki, attempting to cut Yuuka. Yuuka parried them with her parasols and the flowery sword she "stole" from Mima.
{Marisa's thievery rubbed off of her.}
"Fortuna Forge." Shinki muttered as her sword-like wings turned into giant battleaxe, crushing through Yuuka's parry.
"Fortuna Forge?" Yuuka gasped as she slid back. "You're bringing out the big guns already?"
"This is not a sparring session, Yuuka!" Shinki barked. "I'm here to kill you!"
"Then come get me with everything." Yuuka smirked, her sadistic needs insatiable.
"Very well." Shinki grimly smiled, and faced John. "You intruders want to stay even farther back."
"Mobius World - World's End!" Shinki shouted. Her entire body glowed as spirals of omnipotent energy revolved around her, eating everything in its path.

"Apocalyptic Spark!" Yuuka tapped all of her power, streaming them into her parasol. Shortly after, a laser, enveloping the entire valley, was fired. When the omnipotent spirals collided with the laser, a sphere appeared from the collision site.
