Oh, that was a very good story! The genre itself was promising, but you definitely didn't disappoint with your maf writing skills either.
I loved how you used the idea from The Darkness Within, one of the creepiest episode in the series. I never expected it until the reveal.
You didn't have too many screw-ups when it comes to Japanese, but one you repeated many times was "ouji-san" instead of "oji-san". Fun fact, "ouji" means "a prince", so I suppose that was not what you meant to write.
Also, I can't agree with Raph not being good with kids. In the 2003 series he proved a few times he was in fact pretty good with them Well, even in your story he was doing a decent job, I mean better than I would anyway.
One thing that really bothered me though Mikey's problem. Like, I can't understand why he believed in what that guy said, not just for a moment but really deeply.
Anyway, I really enjoyed reading this story. It's not often that I have a pleasure to read a good work of TMNT fanfiction with Usagi playing a big role. He should've used an older kind of Japanese though, but since you said you didn't actually speak the language yet, I understand how difficult it must have been to even use as little of it as you did.
Keep up the good work :)

His son is Jotaro

...I want to be you when I grow up. (I'm in my 30s)

This is one of the greatest pieces of fanfiction I have ever read. This is a masterpiece.

My sweet Mikey, my sunshine child, my cinnamon roll.

I feel like he is the reason why I love the literary trope Break The Cutie.

You broke the cutie. You made him into an Iron Woobie. I love you.

Awesome story, so happy I discovered it :)

This whole epic of adventure amazed me. It's filled my down time gloriously and brightens up my lately dark feelings and mind-scape. Happy endings are what I need right now. Thanks very much.
3

And now I've seen more Bishop, this bs he spews here makes so much more sense. Jackass.

All hail Usagi, feudal samurai techno-wizard!

Ahh Leo. In the dictionary next to the word self-sacrifice, I swear there's a picture of him.

Annndddd NOW Usagi in jeans is finally worthy of me cracking up instead of just grinning. Only Mikey would dare.

Ahh, and now to put down some thoughts on this amazing piece of literature you've written.

First, I would like to say that I love how you write, especially how you write character, drama, and their interactions with it. You have this amazing way of writing things so that everything is neatly wrapped up and there are no holes, yet nothing is over analyzed. It's a very fine balance and it's great how you do it because I WANT to re-read your stories, just so I can analyze them again. I as the reader do my own over analyzing, allowing for fresh perspectives from time to time, rather than having the writer hand it to me on a silver platter. It's so fun to read. And there's no over drama to the point of angst or emo either!

Also, you do great family fluff. You do great fluff in general, with a masterly handling of the characters that keeps them IC and yet allows them to grow. I can always believe the character would do and say exactly what you write them doing and saying. I've noticed in R&C fan fiction you write as well.

Now to this story. I'd like to take this opportunity to point out the cliff hanger where Raph yells out the Mikey wasn't breathing and point my finger in your face and say "You, are an EVIL person."

That out of the way, you did a nice job of keeping me guessing. Of course I knew Tibalt had screwed with Mikey's head. And of course I knew he needed to talk about it before it would get better. But you did such a nice job of keeping me in the dark.

Also, fun fact, I had not watched enough of TMNT before starting this to fully appreciate Leo and Raph's freak out when Mikey came home. Ironically enough, as I watched the 2003 series more and went back to that scene, it's impact increased, but it was actually pretty good when I first read it. I could sense the special rage that only comes from seeing a family member do something stupid that gets them hurt(I have kids, I know this sensation farrrrrr too well. In fact, I'm pretty sure I've pulled a few Raph blow ups and at least several Leo lectures in my life already!)Of course, now that I've seen more of the series I know this is kind of a specialty of Mikey's, so I understand it more. Still, even without total context the scene still played out fairly accurately.

Love that Raph got to be the one to get Mikey to open up. Did it well, did it without going OOC, and just overall made me a happy fluff-loving person.

Mikey's near death, just...awesome. Totally had me going there, I practically cried, and loved EVERY MOMENT of it.

Brotherly bonding fluffiness! Love it!

Adorable Mikey is Adorable. This is why he's my favorite.

Wait, wait, wait! "Darck chamber under an old mansion" tibalt is that evil comet freak thingy?!

I am so proud of my dear turtles
This really was a good chapter

;_;