After I saw this, I asked my friend to translate this… He’s not perfect at Japanese and I don’t if this is all 100% correct, but this translation will probably help someone so I’ve decided to share it with you. If somebody who knows Japanese better sees some mistake, please correct it.
Rivaille: Get in.
Rivaille: What are you doing? Quickly, get over here.
Eren: What…? So suddenly… I’m an idiot for coming here.
Eren: What? No! Wait, don’t tie me!
Rivaille: But this way… We can do this properly.
Eren: Seriously… What’s gotten into you now?
Rivaille: You see, Eren… I’ve been thinking what are you taking me for?
Eren: Sto… Shit! Why am I shaking like this?
Rivaille: It can’t be that… You can’t bare something like this?
Rivaille: Take a good look.
Eren: Such a thing… I don’t know.
Rivaille: You’re not scared, are you? That would be funny.
Eren: Is that so…
Rivaille: Ooh… About the thing I want… Do you have the confidence to say it?
Eren: Ple… Please start already…!
Rivaille: Heh… It’s so big.
Rivaille: Now, after that…
Rivaille: What is it? If you don’t say it properly, I don’t know.
Eren: More… I want more…
Rivaille: It’s okay. I’ll put it in.
Rivaille: What’s wrong? Should we stop?
Rivaille: Ah, I’m coming…
Rivaille: From now, you should know one thing: I love you.