Author's Note: I'm getting a divorce which is why I haven't posted anything in ages, I am also going to put most of my stories on a hiatus in favor of new ones because I used to read my writing (as well as loads of other books) to my soon to be ex-wife before bed and that's just real damn painful. So have a catharsis piece I am writing mostly for myself y'all.
Anyways this uses a custom mix of Power Ranger and Super Sentai lore. As it would kind of suck to have all the 'modern' Ranger teams be from the US, Canada, and New Zealand if I followed pure Ranger lore. I also stretched said timeline out a bit. A new ranger team every 1-3 years feels ridiculous even from a tv show canon standpoint, haha.
Episode 1: Rabbit Hole
Izuku Midoriya was a bit of an overachiever when it came to anything pertaining to heroes in his classes. Literature essays were usually on hero novels or stories and folklore that inspired heroes, history projects somehow always twisted back around to the topic if possible, and his math and science interests all focused on the physics of superpowers or the technology of support items.
So for his final history project of his second to last year of middle school Izuku decided to write an analysis of which aspect of ninja legends had most inspired heroes like Edgeshot.
He'd thought his historic research would mostly end in the ancient Tokugawa Shogunate, as that was common knowledge as when ninjas were last active in any real organization. He figured that after that it would all become movies and books and comics.
He was thoroughly surprised when he found references to multiple mysterious teams of ninjas cropping up throughout pre-Quirk history. There was a group in the eighteenth century where it was debated about whether they were emulating ninja or samurai, as they had some kind of mixed aesthetic and supposedly used 'ninjutsu-like abilities'.
The next one didn't crop up until the late twentieth century, first small scale sightings in the Minato Ward that might have been connected to a few other groups with different aesthetics. And were for some reason connected to Yokai legends going back to his other research on Sasuke Sarutobi, though he couldn't get anything specific on how they were supposedly connected frustratingly enough. Then in California of the United States of all places. These groups were seemingly connected to a line of strange reports and seeming folk tales that had no photographic or videographic evidence backing it. And while post-Quirk chaos had lost far too many artifacts, books, and computer servers full of important data, somehow Izuku doubted that DINOSAURS and giant animals of all things running around wouldn't have had their recordings widely spread enough to make it through the chaos. Those sightings of connected groups went right up to the disastrous Terra Venture project, humanity's first and last major space expedition before Quirks emerging caused society to focus back inwards on internal discovery as opposed to external. Or that was what he thought about the lack of new space exploration at least.
Next were much less blatant sightings, once more back here in Japan, no less than three different groups spread out of the next fifty years involving the shinobi or samurai aesthetics and strange reports of ninjustu-like powers.
The most intriguing thing for Midoriya though, was that the final sighting of any of these strange groups, ninja-themed or otherwise, preceded a gigantic explosion over the Australian Outback supposedly involving prototype military technology that no nation seemed to want to claim just less than a year before the birth of the Luminescent Baby.
A few academic papers he read on the subject used the lack of concrete evidence to dismiss the possibilities that these were organized but secretive early-Quirk users fighting similarly powered and secretive villains. The primary theories were that either fiction had gotten mixed into the historical record by word of mouth after Quirks had appeared or that they'd merely been rogue vigilantes or a paramilitary group using stolen military technology, similar to the groundbreaking technology that had gone into the Terra Venture project. The last was especially held to as none of the reported effects hadn't been replicable by modern scientists making Support Gear for heroes or the hero academies. They simply assumed it had been experimental technology that by its secretive nature had been lost when many governments fell into chaos after Quirks became widespread before things calmed down.
But Izuku was very intrigued, because one of the teams that reportedly used strange powers or technology had been active in Shizouka Prefecture! He was going to come back to this topic over the summer after he finished this paper. Because this was a very interesting mystery, and it combined two of his favorite things! Studying and heroes!
Well general studying wasn't one of his favorite things, so really just his favorite thing, heroes!
With a yawn he stretched his arms and back out in the seat he had taken in the Mustafu Municipal Library, looking at his Official All Might Limited Series Four watch he saw he'd been absorbed in chasing that mention of late pre-Quirk ninjas down a rabbit hole for a solid hour more than he'd planned. His mom hadn't called yet though, so likely she wasn't worried.
"Still, probably means I'm reheating my dinner again…hehe, oops!" He said abashedly but quietly to himself as he gathered his notebooks and essay as well as placed a few books in the return cart but brought a few more over to the library's self-checkout kiosk.
He walked in the door to see his mother sitting on the couch sipping tea while watching the news, it looked like Endeavor had stopped a serial villain earlier that day, he'd have to look up articles once he had his dinner.
"Zuzu dear! I was almost going to start getting worried! How was the library?"
"Oh! It was great, Mom! I got a bit lost down a barely related subject I came across, can't use it for my essay but that's already done! I think I might want to do a personal research project on it over the summer for my summer reading! Of course it really isn't that extensive of a requirement, but it's just so interesting if I have to read books I may as well read ones I am interested in! And it might give me a reason to get out and see some other towns in the Prefecture, would that be alright, Mom? I mean it would all be safe places I can get to by train or ferry and it's just really interesting old folklore stuff and…Mom? Mom!"
Inko Midoriya was just blinking back confusedly at her son as he rambled on until he noticed he had lost her, "Uh…that sounds wonderful, dear? I have no idea what you mean about folklore but getting out of the house over the summer sounds wonderful! Perhaps we could make a small trip of it the first time? Just to make sure it's safe if you need to go back to places?"
Izuku nodded furiously with a big smile on his face, "That sounds great! I'm not sure exactly where I am going to end up needing to go, but I have narrowed things down to the Izu Peninsula and maybe parts of what used to be the old National Park out there!"
"Oh! I love the Fuji area! I hope it ends up being one of the beach towns you need to go to!" Inko let out an exaggerated laugh to let him know it would be okay if it wasn't, but that it still sounded like a very fun idea if it was the case.
Thus Midoriya turned in his essay and wrapped up the school year, excited for the summer and oddly for a kid his age, to get back to the library.
It took him almost two weeks of daily research both in the library and online to narrow down the hearsay, folktales, and legends about a group of oddly equipped, either through technology or powers, individuals operating as far as he could guess perhaps off of some hidden location on Izu Oshima Island in the Sagami Bay. Or at least that's where he would have hidden a secret base in the mid-twenty-first century if he were doing strange vigilante work across the Izu Peninsula and was trying to hide advanced technology that possibly included giant robots as well.
He excitedly told his mother, who in turn was excited as the island's beach resort had been rebuilt when she was a child and she'd actually taken a vacation there with her own parents when she was seven and was excited to get to go back. She put in to have a long weekend from work the next week and ordered a two queen-bed room at one of the mid-range hotels by the beach for them. They'd take the ferry in from Atami on the peninsula and Izuku could take public transport a bit inland to explore the nature park around the dormant volcano.
In fact, the fact that the volcano was dormant was extremely suspicious to Izuku. As the last recorded eruption right before it had mysteriously and suddenly gone completely dormant was the night before the explosions over the Australian Outback. Of course nothing other than timing actually connected any of these groups to either of those events.
But that last eruption had also dramatically changed the topography of the island and the volcano from what Izuku could tell. The pre-dormancy maps compared to the after dormancy ones showed a completely different size and shape to the mountain. It completely jutted out at an entirely new point in an odd amorphous triangle. Almost like it had tried to create a new mountain next to itself and failed.
That was the area he was planning to explore the most. Wouldn't it be so cool if their secret base had been covered by lava or something and it was just there waiting for him to discover?
"Don't be ridiculous," He chided himself. Nothing man-made could survive being totally covered like that. Even if it had been covered by the lava flow the best he could hope for would be a few interesting artifacts that had gotten blown free of the blast. Completely possible if he was right about the location, as there hadn't been any archeological work done on the volcano proper since before the eruption. All the modern excavations were on the old resort city area, which had been completely overcome with ash, almost like a second Pompei.
Regardless, Izuku went to bed that night excited for the coming vacation. Even if he didn't find anything he could at least enjoy the beach and time with his mom!