Your ask was kind of long so I decided to make a separate post, I hope you don't mind @idiotcauseitsfun
This is a part of 3x Valentines event (All slots are taken)
Cw: character death, major v3 spoilers
Unsent confession letter from Rantaro to mastermind reader
You realized that you might've gave him a bit too much room to roam around and investigate. As much as you hated to admit, it was obvious that he was getting suspicious.
He avoided you more and you knew when he was lying to you about what he was up to. After all, you had the cameras to prove it. Perhaps he wanted to test you, but you weren't dumb enough to fall for his baits.
It was dangerous to keep him around, so you only waited for the right opportunity to get rid of him. Honestly, you had no idea why you'd use him for a killing game again considering how well he did it the first time.
Maybe some of his memories were coming back? Or maybe it was a gut feeling but he definitely was weary of you.
How perfect it was that Kaede had her plan, it gave you the perfect opportunity to get rid of him before it was too late.
You didn't have a lot of time so you took whatever you could just in case he had some evidence on himself that linked you to being a mastermind.
When you took them into your room and started looking through the things. A piece of paper caught your attention.
I figured it'd be best if I write this down just in case something happened to me before I get to tell you directly. As much as I hate to admit it, I think you might be the mastermind, at the same time I try to make excuses for you in my head because I've fallen in love with you. I don't know how did it happen so soon, but maybe before the memory loss I've already felt something for you and it stayed with me. I'm honestly not sure of what to think about all of this. It's really getting to me. Because I can't imagine you being behind all this and yet everything I've gathered so far points at you. It drives me even more insane that I think that while being in love with you. But since you're reading this, I don't think my struggle of understanding it matters. It's sad really, I probably died without knowing the truth and if I'm wrong about all this my final words to you are just accusing you. So it's time to switch things around a little.
No matter what happens, remember that you're special to me. I don't remember much, and we haven't had the chance to spend so much time together either. But if you managed to make me fall in love in this short amount of time it only shows how charming you are, no? Your attitude and strong personality is like a magnet that always made me want to be around you. Just make sure you always stay yourself, no matter what others may think or say.
I guess that's my final goodbye then,
Looking through it you were surprised... Although you suspected that he had feelings for you doing your previous run of the game, you were sure that he'd given up on it and end up forgetting it anyways.
But in the end what he felt about you doesn't really matter. You can't respond to a corpse.