Since I'm at it, I've spent the evening checking the translation of the Guillotine Masturbation part. Disclaimer: I've never formally studied Japanese, just watched a lot of anime so that I have enough feel for it to see where Google Translate is off.

The right-to-left translation seems mostly correct, but there are some inaccuracies and liberties.

Main errors of the existing translation:

- Akira doesn't ask "Do you have any doubts", he asks "Are you still conscious?" So there's no implication of any sort of doubt.
- Akira doesn't say anything about "Great present", he says "It was the BEST feeling..." So there's no implication of it being sister's present to him.

Here's my whole translation (rough draft in term of phrasing, but meaning should be accurate):

気持ちいい？お姉ちゃん
Does it feel good, Onee-chan?

い．．．いいよもうイきそう．．．あっ
G...good! I'm about to come... Ah

お願いアキラ言ったとおりしてね
Please, Akira, do as I told you.

うんわかってる
Yeah, I know.

あ．．．．．．あひっ．．
Ah... Ahh...

いっ！！ いくーっ！！
Co... coming!

***

あ．．．．．ああ．．．
Ah... A-ah...

あたし．．．．．．斬首されてる．．すごい
I... I've been beheaded... Wow

お姉ちゃん．．．まだ意識ある？
Onee-chan... are you still conscious?

***

ほらお姉ちゃん見て
Here, Onee-chan, look!

すごい．．．あたしの体．．．
Wow... my body...

あたしのまんこ．．．
My pussy...

まだヒクヒクしてる．．．
It's still twitching...

なめてみたい
I want to lick it

お願いアキラはやく
Please Akira, hurry up

ん．．．ちょっとしょっぱい
Hmm... It's a little salty.

これがあたしのまんこの味なのね
So this is what my pussy tastes like.

***

ああ．．．だんだん気が遠くなってきた
Ahh... I'm starting to gradually lose consciousness.

アキラ！最後にアキラのをしてあげたい
Akira! At the end I want to do you.

僕のをしてくれるの？
Will you do me?

お姉ちゃん．．．．．．
Onee-chan...

すごい．．．！！アキラのおちんちんはちきれそう．．．
Wow...!! Akira's dick looks like it's about to burst...

あう．．．お姉ちゃん！！
Ow... Onee-chan!!

出ちゃう．．．！！
It's coming out...!!

アキラ．．．あとはアキラの好きなように．．．して．．．．
Akira... From here on, do as you... please...

***

ありがとう．．．．．．
Thank you...

お姉ちゃん．．．
Onee-chan...

ここで見てて．．
Watch from here...

いいよねお姉ちゃんセックスしても
It's okay to have sex too, right, Onee-chan?
(literally: "even to have sex")

お姉ちゃんのおまんこ．．．まだあったかい
Onee-chan's pussy... still warm

***

気持ちいいよぉお姉ちゃん！！
It feels so good, Onee-chan!!

もっと
More...

もっと前へ．．．．．．
More forward...

(I'm not sure about the exact meaning of forward here or how to better say it in English, DeepSeek says he's asking her to push her hips more forward (so towards him? as in fuck back?), even if I explain to it the story and situation of her being dead and unable to do that, it still says that's what he must mean in the heat of the moment)

***

あっいいっ
Ah... good...

お姉さん僕もお姉ちゃんといっしょに．．．．．．
Onee-chan, I too together with Onee-chan...

もうだめお姉ちゃん
I can't anymore, big sister

僕出ちゃう！！
I'm coming!

いっ！！
Co... (cut-off coming)

***

いぐっ！！
Gum—!! (distorted and cut-off "cumming")
(his neck is being cut off, so c becomes g)

ああ．．．．．．
Aah......

こんな感じなんだ．．．．．．
So this is what it feels like...

Sfx: ぼふっ
*poof*

***

サイコーに気持ちよかったよ．．．
It was the BEST feeling... (deliberate emphasis on the word "best")

おねえ．．．．．．ちゃ．．．．．．ん
Onee-... cha-... n...