The 27th Day of December in the 15th Year of the Heisei Era.

13 kilometers north-northeast of Umihotaru, an artificial island located at the midpoint of the Tokyo Bay Aqua-Line.

"Why...?"

That was the only word that could leave the woman's lips as she fell to her knees, cradling the barely two-month-old child in a desperate attempt to not let him drown. She had the ability to tread the water surface, taking advantage of the natural properties of the liquid. Beneath her, the surface tension that held water molecules together strained to keep her from descending into the waves. Every second, the woman could feel her strength draining away as she slowly began to sink. However, she refused to let the child in her arms, her beloved son, to touch the water.

"I thought you loved me...!"

She raised her voice in another desperate cry as she turned her head up. In her sights sailed a small passenger ship belonging to the Japan Coast Guard. On its bow was a man, whose unkempt hair clashed with his well-dressed demeanor. He tugged at his black silk tuxedo, straightening it out before turning away. The woman caught a look of contempt in the man's countenance in that final glance. In that man's place, a woman, dressed in a white military-style uniform, appeared on the crown of the ship before drawing the two swords at her waist.

"Men are cruel," she declared. "However, I would say that fate is even crueler for you. To have fallen in love with a human, even siring a child, is beyond preposterous. I'm afraid the infant will need to die along with you."

The woman in the water could hardly make another sound as the woman on the ship jumped off and began attacking her, joined by an entourage of seven other women. However, she refused to let the child in her bosom go even as she was covered in wounds. In her final act, she said a prayer to her child, granting him divine protection and unleashing a blast of light before using the last of her powers to latch onto the dual-wielding woman.

As proof of his mother's divine protection, the child was spared.

Excerpt from the first edition of The Japan Times released in the 16th Year of the Heisei Era;

The Great Catastrophe of Tokyo Bay: Special Sword Administration Bureau Report

A large cargo ship departing from Tokyo's Minato Ward carrying 285,000 kilolitres (cubic meters) of extracted yousai began spontaneously leaking at 1338, December 26. Upon contact with the ocean water, the yousai began to coalesce into the largest aradama in recorded history, roughly spanning a circumference of 35 kilometres. Toji from the nearby prefectures were all immediately deployed in order to counter the massive aradama but to little effect. Emiri Arisugawa, Azusa Hachimiya, Manami Kuzunoha, Asuka Mitsumine, Kotori Nekoyanagi, Nanae Origami, Chikage Serizawa, and Madoka Shinonome, the most powerful representatives of The Five Traditions, joined the following day.

It took another fourteen hours of nearly continuous fighting for these eight girls to finally manage to destroy the massive aradama. Due to the miraculously well-placed timing of the leak, civilian casualties were minimal; only the crew suffered losses with 7 of the 24 onboard confirmed deceased and the rest with varying degrees of injury. The losses to the Toji were nothing short of catastrophic. No Toji escaped unharmed and a total body count of 1037 of the 5250 Toji deployed was given. The deceased Toji would be released back to their families and would be put to rest in the ways of their family.....

The 23rd Day of October in the 30th Year of the Heisei Era.

The Third Training Arena of Osafune Girls' Academy.

Okayama, the capital of Okayama Prefecture.

On the polished wooden floor stood two young girls opposite each other at a roughly equal distance from each other, standing north and south. To the west stood their examiner and to the east, a group of spectators. In their hands were wooden bokuto, training swords. These two girls were the finalists of the intra-school tournament that would determine the four students that would represent Osafune Girls' Academy in the 123rd National Swordsmanship Tournament. They were friends yet at the same time, enemies.

The girl with naturally silver hair made the first move. From her natural seigan stance, she charged forward, diagonally slashing from her right. However, her violet-haired opponent, in the deceptively offensive gedan-no-kamae, perfectly blocked her strike. She drew back her sword and made a sweeping slash from her right but is countered by her opponent drawing her feet back and to her right so as to bring down her blade against the blunt surface of the silver girl's blade, the violet girl dragged the silver girl forward. However, the silver girl quickly regained her footing, reversing her grip on her blade and thrusting backward which is caught by the violet girl's blade. Pulling forward, the silver girl quickly turns around, recovering her stance.

She enters in-no-kamae and makes another charge, a vertical slash which the violet girl's joudan-no-kamae deflected. Having brought her sword forward from that stance, she caught the silver girl's sword against it, allowing it to fall downward, scraping against her blade the entire while. However, the violet girl failed to catch the silver girl's counterattack where she pivoted on her left foot, spinning in place and striking the violet girl's open right flank (left from the silver girl's perspective).

"Stop right there!" the instructor announced. "The winner is Arisugawa!"

Both girls returned to a seigan stance before easing themselves. Holding their sword at their hips, they bowed to each other before proceeding to exit the arena and heading toward the First Training Arena which was already fitted out for the awards ceremony. Before their match began, they were instructed to enter the First Training Arena and assemble on the stage after finishing their duel, regardless of the winner. Awaiting the two girls (along with the other two girls that they had respectively defeated in the semifinal match) was the school principal, Chikage Serizawa.

"The winner is second-year junior high student, Suzuran Arisugawa." Chikage took a laminated piece of paper from the podium and handed it to the silver girl, Suzuran. It was the certificate that denoted her victory and her qualification of representing Osafune.

"Yes, ma'am." Suzuran walked in front of the principal and took the piece of paper before bowing.

"Congratulations," Chikage added.

"Thank you very much!" she replied, proudly puffing out her chest before returning to her place in line with the other four girls.

"The runner-up is second-year junior high student, Honami Mitsumine."

"Yes, ma'am." The violet girl, Honami, stepped forward, receiving her certificate in much the same way as Suzuran.

"Congratulations," Chikage repeated.

"Thank you!"

This repeated itself twice more for the two other representatives, a girl with brown hair named Reina Nekoyanagi, and a girl with rose blue hair named Kaguya Nakamura. The principal then guided the girls, lining them up in a way that they were all facing the assembled students, declaring, "These four students are Osafune's representatives! They have fought tooth and nail through the selection battles against their fellow students and have proven themselves to be the best Toji of the year! Please offer them your sincerest congratulations!"

At that, great applause exploded into existence. However, in the case of Suzuran Arisugawa, she did not register them. She was busy off in her own world as she contemplated the upcoming days. She wondered to herself, what sorts of wonderful swordsmanship styles would she have the pleasure of encountering, perhaps even clashing against, during the tournament? These giddy thoughts carried with her all throughout the day, ruining her self-awareness to the point that she needed assistance in getting ready to depart when she would normally need none.

Same time.

Hiiragi mansion, located near Heijou Institute.

Nara, the capital city of Nara Prefecture.

Caught shimmering in the afternoon light were the fair black locks of a girl. She was a student of Heijou Institute and had recently escaped from the awards ceremony. She had already packed her bags so there was no need for her to dilly-dally in Nara any longer. However, before she left, she wanted to stop by her family mansion one last time.

Opening the door, she entered the house, taking off her shoes and whispering, "I'm home." Of course, no reply came. She traversed the complex until she found the place she was looking for. She bent over and inspected the altar where a picture of her late mother, Manami Kuzunoha, was enshrined. She then pulled out the drawer and reached inside, fiddling around with the false end. Extracting that, she removed the item hidden behind the false wall: a letter with the name Manami Hiiragi-sama on it.

The girl knelt down in the formal seiza position and put her hands together. She prayed to her mother while also steeling her resolve. Once again, the girl, Noa Hiiragi, swore an oath to herself.

It is time... I shall exact vengeance upon you! You, who drove my mother to despair...! Nanae Origami...!!

The 24th Day of October.

Just outside the ticket barrier at JR West's Okayama Station.

"Don't mix up the stations you need to get off at!"

Ever since leaving the academy grounds, Suzuran had been tailed by a group of eleven of her friends, the leader of which deriving excessive joy from constantly teasing her. While it was a consequence of her own actions due to how airheaded she can get when she is excited, Suzuran still found it irritating.

"I'll be fine!" she retorted. "After all, I have Honami to watch my back!"

"Depending on Honami already?" the leader jeered, resulting in an explosion of giggles in the other ten girls.

As for Honami herself, she was busy trying to stay her old butler. "To think the day would come when my Honami-ojou-sama would represent Osafune...! I'm so glad to have lived this long!"

"Ah, jeez, Gramps, quit it!" she yelped. "You're embarrassing me!" She then escaped and talked to the attendant at the ticket booth, showing him the identification card issued to her from the Special Sword Administration Bureau. "Here, this is my identification."

"Thank you for your service, young lady," he replied.

Suzuran escaped herself and followed Honami's example, displaying her information, before waving goodbye to her friends. "Alright, we're off!"

"We'll drop by tomorrow to cheer you guys on!"

"We'll be going now!" Honami added.

"Do your best!" the eleven-strong chorus sang.

Once through the gates, the two girls lined up patiently to wait for the train. Luckily, they were spared from waiting too long as the train arrived not long after. They boarded them, stored their luggage, showed their tickets to the attendants who stamped them and sat down. Five minutes later, the train took off and an hour after that, Suzuran had already ordered lunch from the food cart-pushing attendant that had passed by them. "Train bento..." she drooled. However, one glance at Honami made her change her mind. "But, I guess it's too early to eat."

"Haha, I thought you'd say that." she laughed, before digging around in her purse and pulling out a bag of cookies. "Here, for you."

"Honami's cookies!" Suzuran immediately pounced on them, opening the bag and popping four pieces into her mouth. "Thanks a bunch!"

"I couldn't really sleep last night for some reason so I ended up making these."

"Last night?"

"Yeah," Honami nodded. "For some reason, the sounds of making cookies are very relaxing."

"I love your cookies so it's all good!" Suzuran waffled, her mouth foaming due to her trying to talk while munching.

"Heh, and I love your goofy face as you chow down on them."

"But I mean, they're just so good!" Suzuran punctuated that statement by finishing off the cookies in the bag. She then wiped her lips and asked, "By the way, we should be arriving in the next two hours or so, right?"

Honami pulled out her mobile device and played with it before replying, "Yeah, we'd be changing trains at Shin-Yokohama."

"Oh man, the Origami mansion... The matches held there are legendary."

"You really just can't be nervous, huh?"

"How can I!? We're going to see so many cool swordsmanship styles. Hell, we might even get the chance to fight them!"

Honami could no nothing but shrug. "That's so like you, Suzu."

Afternoon.

Outside of Kamakura Station.

Kamakura, the capital city of Kanagawa Prefecture.

"We're finally here!"

Walking outside with her items in tow, Suzuran stretched her arms, and as a consequence, her predominantly Western-style uniform stretched along with her. Her uniform as an Osafune Girls' Academy Student consists of a white dress shirt with an orange double-breasted midriff, a brown bowtie, an orange-and-yellow open vest with a long collar, and a brown pleated skirt. While she didn't need it due to lacking the chest size, the more well-endowed Honami certainly did as she had a strap under her chest so as to provide a snugger fit around her midriff.

Honami, meanwhile, was tweaking with her mobile device again, muttering to herself, "Um... The Origami mansion is..."

Suzuran pulled her out of her thoughts when she pointed across the street at four girls. "Those are Ayanokouji uniforms, aren't they?" Students of Ayanokouji Martial Arts School wear a uniform that combines the boys' gakuran and the girls' seifuku (although Ayanokouji does not have male students [nor does any of the other four schools for that matter]); it consists of a black inner blouse with a band collar, a white long-sleeved sailor-style shirt with a gray collar and black ribbon, and a long white pleated skirt.

"Ayanokouji..." Honami mumbled, turning her attention to another four-girl group. "Those are Renpu uniforms." In the case of Renpu Girl's School, student uniforms have elements of both the traditional seifuku and the Western-style school uniform; it consists of a plain white dress shirt, a yellow necktie, a beige long-sleeved blazer with a purple sailor-style collar, and a short purple pleated skirt. While it was difficult to make out, a pair of small silver tassels can be found on either side of the skirt.

Honami turned her attention to the last four-girl group, stating, "Those should be Minoseki Academy uniforms." In the case of Minoseki Academy, student uniforms sport a white-and-red color scheme and a design with elements of the seifuku and the double-breasted military coat. The uniform consists of a white long-sleeved blazer with a red seifuku-style collar, a white inner blouse with a high-round collar, and a short red pleated skirt with a small slit on each side. Too small to be seen from afar are the minuscule details added onto the uniform which include a yellow ribbon and tassels on the back portion of the collar.

Suzuran found herself drooling again as she quipped, "Any one of these girls could be my opponent tomorrow!"

Honami, on the other hand, didn't share her explosive enthusiasm. "I guess so. First, we need to find the Origami mansion."

It didn't take the two girls long to find the complex, however, it was extremely massive. It had all of the elements of an old-style Japanese mansion, complete with a pathway leading to a shrine somewhere in the mountains behind the complex. "Whoa... This really is the Origami mansion," Suzuran muttered in awe.

"Yes, this is the mansion of the family that the government had charged with the ability to manage all of the okatana in the country."

Suzuran couldn't help but scan the entire complex but when she turned her eyes to her left, her panoramic view was marred by a lone girl. She was wearing a Heijou Institute uniform which was arguably the simplest out of the five schools: a navy green one-piece dress uniform with a white sailor-style collar, a light green ribbon, and a skirt parted with two large pleats. The Heijou girl looked her way too but didn't seem to have an interest in having a dialogue as she began indifferently walking toward her, her eyes looking somewhere into the unknown.

"Hiya!" Suzuran said. "Um, are you going to be participating in the tournament tomorrow?"

The Heijou girl, however, completely ignored Suzuran as she walked past her.

However, when she did...

Suzuran Arisugawa carried with her the okatana, Suijingiri Kanesada. Formerly named Chidori, it was the same okatana used by her late mother, Emiri Arisugawa. Right now, that sword was vibrating in its sheath.

Noa Hiiragi carried with her the okatana, Yatagarasu. Formerly named Kogarasumaru, it was the same okatana used by her late mother, Manami Kuzunoha. Right now, that sword was vibrating in its sheath.

The two girls had turned on each other and instinctively taken battle stances, their free hands poised over the hilts of their respective blades, ready to draw and engage at a moment's notice.

Silence ensued as they stared each other down.

This was the first fateful meeting between the former Chidori and the former Kogarasumaru.

This was the first time that "resonance" was observed between the mysterious okatana.

This was the first time in fifteen years that three members of the bloodline of those girls that had fought in the Great Catastrophe of Tokyo Bay were reunited.

And, this was the first in a continuous series of calamitous events that would rock Japan to its very core.