[This took a while since I went through multiple styles; unsure how to handle this.]
"Ugh." Rumia grunted; her eyes flickering open for a second. For the brief moment; she couldn't tell where she was. Was she in the living realm; or was she in Higan?
She fell unconscious again anyway.
Then she groaned again. This time she felt pain; and opened her eyes properly.
This wasn't Eientei; but it was indoors. Machines flashed around Rumia.
"Is this... Rika's?" Rumia grunted slowly. She turned her head and saw various medicines; with Eirin's brand on them.
"Well... I'm alive it seems." Rumia said weakly. "I'm sure I saw Eiki for a moment there."
Rika entered the room; and noticed Rumia was awake.
"Judgeing by the lack of screaming you must have just woken up and not noticed yet." Rika said.
"Hmm?" Rumia said; before she attempted to sit up.
"Your body hasn't healed yet. And it won't fully heal Eirin said. You used the last of your energy to clot your blood to prevent death by blood loss; but had no energy at all to regenerate the wound." Rika explained. "With your organs damaged; you couldn't exactly eat; so we had to put nutrients directly into your bloodstream. Eirin did all that she could and handed you over to me. Believe it or not; I'm medically capable with my machines."
"None of that explains why I can't move." Rumia said.
"The damage Titania did with her final attack; it can't be repaired. She erased that section of your body from natural existence. Not even Shinki can undo her final curse; Shinki claims that if she infused you with that much of her energy to overpower Titania's Curse; you'd die long before it. If the wound healed instantly by your regeneration it might have worked before the curse took hold, but you had absolutely no energy."
"I managed to patch you up with cybernetics, but I dare not tamper with your central nervous system. If I do that you could be rendered cataconic outright. You're paralysed from the waist down."
"Well, I can still fly places."
"Yes, but it's still not ideal. I mean, you can't kick people in combat, and you can't stand up or walk around the human village. You have to constantly use energy to fly. It adds up." Rika said.
"Ah; you did what you could." Rumia said. "How long have I been out?"
Rika muttered very quietly.
"Pardon; I can't hear."
"A new record!" Rumia said happily; before she somewhat awkwardly floated out of the bed, before with difficulty righting herself to an upright standing position, floating just above the ground.
"OK, this is more awkward than I expected. I can't even flow magic to my feet to help me fly like usual..." Rumia said, before she put her arms out in the cross position, and stabilised.
Then pain shout through her body and she fell to the ground.
"Ow..." she groaned.
"Oh yes, your body hasn't fully recovered yet. Take it easy. The magic you tapped into to take down Titania... it almost ripped every part of your body apart. It wouldn't surprise me if using magic for a while is painful after magic did so much damage to your body before."
Rika lifted Rumia back into the bed, and Rumia sighed.
"So... what happened to everyone else?"
With Titania killed; Gensokyo, and the other dimensions, went back to its 'normal' state; although rebuilding and gardening was required.
Rumia needed some time to adapt to her loss of use in her legs; but it only took a few months for her to fully adapt; after which she was almost as agile as before. However, she was never quite as strong as in her hayday.
Rumia continued being a prominent youkai; and the primary youkai to get involved in incident resolution. However; she settled down and became less active with incident resolution somewhat after thirty years, getting a 'stable' occupation as the ambassador between Makai and Gensokyo. Rumia ensured that Gensokyo and Makai would not come to blows again, even if some crazy youkai or demon decided to take their personal issues out on the other world. She would still get involved in major incidents; but allowed others to handle most of them.
Ultimately; Rumia became a youkai with the same sort of weight held to her name as Yukari once had, after many years. A powerful and wise youkai that had seen a lot; and generally knew what she as talking about. Unlike Yukari; however; she was generally liked and trusted, and a lot easier to understand. She never returned to her height of power, usually using more than 80% of her power for more than a few seconds would wrack her body with pain. Of course, the number of those in Gensokyo would could force Rumia to fight at that level could be counted on both of her hands.
Rumia friends all stayed with her, and together.
Cirno and Daiyousei; along with the other fairies; became slightly stronger; and somewhat smarter upon Titania's defeat; almost as if her power flowed down into them. Remembering their heritage; many more fairies began wearing sunflowers. Of course; this never stopped the fairies being chaotic and child-like; even if they were slightly smarter; they were still not smart by and large.
Mystia continued her work; making her horde of shiny objects larger and larger; while bringing humans and youkai closer and closer. One day; her horde became so large that it attracted a western dragon from outside the boarder; which claimed the horde as its own. Mystia almost died when she attacked the dragon to try and reclaim her horde; to which she stated it was the stupidest move she had ever made. Mystia passed away peacefully after a few hundred years; due to a combination of age and illness; Night Sparrows not being a type of 'eternal' youkai. This did not happen before Mystia found a husband; however; a human male. She had two half-youkai children; natural to one who did so much work to bring humans and youkai together. A small statue of her was built in the human village after her passing; near her restaurant.
In a similar fashion; Wriggle lived out her life in the same way Mystia did; sticking to her calling of commanding the insects. She died a few years before Mystia did; but not before she saw another insect become a youkai; a very rare event indeed due to the usual lifespan of insects. Wriggle took this new youkai under her wings and taught her what she knew; raising her as a successor.
While it took her several multiples of her lifespan at the point where the story ended; Kogasa finally became an 'adult' youkai; mastering her ability to cause surprise. Ironically enough; shortly after this Kogasa became bored with constant success; so stopped using her powers and attempted to surprise people 'The old fashioned way'. She was still awful at it, and always was. In fact; Rumia swore she was worse as a mature youkai than when she was a 'newborn'. Kogasa stayed living in the Myouren Graveyard; along with Yoshika; the two being the best of friends. She also continued to frequently visit Kaguya; who would happily repair her umbrella as natural wear and tear took it's toll. Kogasa; every few hundred years due to un-repairable wear; transferred to a new umbrella; learning how to do this from a drum Tsukumogami called Raiko.
Maribel filled the hole left by Yukari; as she was destined to do. A few years after Maribel became a youkai; Renko transcended into being a Magician as well. As Yukari wished; Maribel became a better person than Yukari was; her human charm; imagination; drive and social nature making her far more open than Yukari; and able to solve issues better than Yukari would. Renko helped Maribel whenever she could; and was always by her side. The two occasionally visited the Outside World for brief periods; just to see how it was developing. Occasionally Maribel and Renko would bring things back for the Kappa or Rika to tinker with and reverse-engineer; making full use of Gensokyo's now-completed electricity network; powered by the Nuclear Generator Rika had tried to steal years before.
The pair always respected Rumia; and often the two asked Rumia for advice. Later; Rumia would ask them for help just as frequently; but the pair always saw Rumia as the superior.
Maribel; after a few decades; became powerful enough that she made Ran her Shikigami; just as Yukari did. Ran was ecstatic at this arrangement; and became far happier than she had ever been since Yukari's death when in Maribel's service. Maribel treated Ran much more like an equal than Yukari did; despite Ran frequently insisting that she call Maribel 'Maribel-sama'.
As for Rika... it took her a few upgrades and new versions; but she finally managed to figure out her feelings for Rumia were love. It took a few more decades after that for Rika to finally admit it. The two became an occasionally awkward -yet close- couple; and Shinki; overjoyed at the prospect of being a grandmother despite the fact it was biologically impossible [And the fact that Rumia was technically not a blood relative to Shinki]; created a 'child' of the pair using her power of Creation, and a little bit of both's DNA [Rika's robotic body having her DNA inside it as part of its design to make it 'Rika'].
Rika never lived up to her promise to kill Rumia. Eventually; Rika's mechanical parts and memory became beyond repair; even by her drones; and she began to deteriorate. However; moved by Rika's change of heart; the Yamaxanadu offered Rika something that she had offered no-one before due to the nature of her life; technically being dead for many years. The Yama offered to place Rika's soul; that was in her possession for all those years; into a new youkai body; essentially a complete reincarnation; instead of a mere spiritual one; knowing that if Rika had truely reformed; she would accept even a Youkai body. Rika accepted; the ultimate display of her acceptance of youkai and changing of her ways.
As for the rest of Gensokyo and other realms...
Makai remained the chaotic plane it always was. Nothing really changed; although the Heart seemed less aggressive; possibly calmed by Rumia saving its brethren; knowing without Shinki's actions; it and all of its 5 brethren could have all been enslaved. Abominations still formed on occasion; but they too were less violent; and did not actively seek dimensional portals.
Eientei too; remained the same. Rabbits were born and died; although Tewi never passed; nor did Reisen; thanks to their strong youkai powers combined with being touched by Kaguya's power of Eternity. Mokou and Kaguya kept fighting; equally out of their grudge and stimulation. Eirin kept contact with the Moon; as she always had.
The Scarlet Devil Mansion did not truely change; but it became more open to visitors. Remilia's harsh nature softened up over time because of Flandre's return to sanity. While she never stopped being proud to a fault; Remilia was a far easier person to get along with. With her mistress becoming more social; Sakuya softened up somewhat too. Eventually; everyone figured out there was no way Sakuya was human since she did not age; although only a select few knew the truth of her lunar heritage. Patchouli remained in Voile most of the time; although it was noticed that the library slowly grew, more and more books being accumulated. Flandre occasionally got involved in incidents herself, sometimes causing problems out of boredom, and sometimes helping to solve them. She also occasionally went underground for a span of days, enjoying the company of many of the youkai there, as well as the darkness. Meiling resumed her guise of being a gatekeeper, and everyone treated her as such, due to this being her choice.
Youkai Mountain; however; went through a period of rapid changes. Kanako and Suwako did not survive their injuries; the pair having been in the process of dying for years beforehand due to a lack of faith anyway. However; people and youkai still came to the Moyria Shrine; and all the faith generated; usually split between Kanako and Suwako mostly; channelled entirely into Sanae. After a few years; Sanae awakened as a Goddess in her own right; a Goddess capable of performing Miracles; actions that would defy common sense. Sanae herself did not change, besides her eyes becoming golden. She kept her snake and frog ornaments as honour to the gods who raised her. Sanae remained good friends with Maribel and Renko, and received more than enough faith from Gensokyo to flourish, although she was very careful about using her powers over Miracles.
In addition; upon returning to Tengu Mountain; Lord Tenma decided to reform the structure of the Tengu Village. Seeing the Wolves and the Crows work together in the Battle of Tengu Mountain convinced Tenma that he was no longer needed to mediate between the two races; so he stepped down as the ruler of the village. Tenma instead re-formed the ruling of the Tengu Village into an elected council; made of equal members of Crow and Wolf; as well as Kappa. Tenma himself stayed away from directly being involved in the new politics; although he was often called upon for guidance and advice. The old Tengu roamed Gensokyo for the rest of his life; making up for what he saw as lost time spent in the village in his ruling days. After a hundred years; Tenma; very much in the twilight of his life; went Underground. He ended his days with the Oni; reliving the start of his life when Tengu and Oni lived together; all the while wanting to make up to the Oni what he had done due to Kasen's manipulation. Tenma died with no regrets of old age.
Momiji; Nitori and Hatate all found their ways onto the new council; and Aya only did not because she had no interest in being involved; instead wanting to dedicate herself to the Bunbunmaru. One of the first things the new council did was improve trade and relations with the Human Village; with help from Keine and Mystia.
The youkai of the Underground continued life as they always had; although Kanakuma's addition made the parties even wilder. Eventually; a new group of Satori entered Gensokyo; Satori previously herself thinking she and Koishi were the last of their kind. The newcomer Satori were shocked to see the Komeji sisters respected in a society; and even more shocked to be [relatively] welcome; provided they were not arrogant with their mind-reading. Eventually; Yuugi; Suika and Kanakuma all died of Alcohol Poisoning; after many; many years. In their stead were the first 'Devas of the Underground'; the strongest of the next generation of Oni.
Tenma's period Underground; combined with the new council of the Tengu and Kappa repaired relations between the Oni and the other races; although the Oni never returned above ground in any major capacity; since they were perfectly at home underground. However, they did visit above ground slightly more often.
Marisa eventually became a magician-youkai herself; and while they never became an official couple; her and Alice were seen together incredibly frequently. Alice managed to make an animate doll eventually; using a piece of Marisa's and her own magical essence; condensed into a single crystal. Rumia and Rika made no hesitation about pointing out the similarities between what Shinki did for them and what Alice did; and Shinki always referred to the Doll as a 'Granddaughter'.
Reimu; on the other hand; passed away at the end of a natural lifespan; aged 78. She had three children; a boy and two girls. Unlike tradition for the Hakurei family where the eldest would be the new maiden; both girls decided to share the burden of being the Hakurei Maiden. Reimu also found a turtle and raised it in the back of the Hakurei Shrine; in the pond. The turtle grew quickly; and developed the ability to talk and fly; just like Genji before it. Strangely enough; the turtle called itself Genji as well; with a very similar personality; leading Reimu to think that 'Genji' was actually a guardian spirit of the Shrine who would manifest inside a turtle. This realisation finally made Reimu return to her old self; whereas before the adoption of the new turtle; she had never quite been the same. The new Genji; as well as Reimu herself, taught the two young maidens what they needed in the Hakurei Arts. They took over for Reimu when they reached 20.
Yumemi did not return to Gensokyo. After the defeat of Titania; she used her devices to trace the Universal Magical Energy she had collected. This led her back to her world; where Chiyuri had succeeded in restoring magic. Yumemi was welcomed back as a hero, and her world was flourishing again due to magic fixing their resource crisis. Rumia never saw her again.
Yorihime and Toyohime respected Rumia for defeating an enemy they could not. The two Lunarians lived their eternal lives on the Moon; only Yorihime occasionally visiting. Toyohime was a beloved Queen; and did not undergo any assassination attempts; unlike every Queen before her. After many years; the two Lunarians stepped down from their positions; allowing their children to take their places.
The Moyuren Temple continued to be a place of Buddhist Worship for both Youkai and Humans. They never saw eye-to-eye with the Taoists; but since Toyosatomimi never actively sought new followers; there was never any conflict or incidents between the two factions.
Finally; Yuuka. The 'True' Yuuka died shortly after Titania left her body; but from her remains came a large sunflower; which when the flower bloomed revealed a child-like Yuuka; innocent and pure, without Titania's corruption. The Gensokyo Yuuka confirmed that this was how she was before Titania entered her body; her natural state. Yuuka 'adopted' her younger self; raising her. Yuuka mellowed out very quickly while raising her other self; wanting her to grow up free to Titania's influence. Elly moved to the Garden of the Sun and helped in this task; raising a child helping take away from the traumas of her past job as a Shinigami. The reborn Yuuka; named Antheia; grew up into a kind; but powerful; woman. She never became as powerful or feared as Yuuka; however. Antheia was mostly known for her seasonal flower festivals she held; and her incredibly strong friendships with fairies. She was the one person they never pranked. Even the most arrogant and chaotic fairies treated her with respect.
Of course, incidents still happened. But Rumia's greatest battle is done, and this is where the tale ends.