The thing is that rape is about the most unpleasant crime our society
can contemplate, and the thought of this happening to a character
(Akane) who, though disliked by some on the list, is virtually a
personal sweetheart to others...well, the thought doesn't sit well.
Despite "moral lapses" (sorry, _Watchmen_ reference) and occasional bad
judgment, Ryoga's an OK guy too. This is a story that I would hesitate
to read much of; nevertheless, since advice was sincerely asked, here's
all I can think of. 
 

1. Ryoga is mistakenly accused of raping Akane when she's found comatose and
naked and bound with a bandanna.

Question 1:  _where_ is she found? This might be a clue as to the
rapist's particular sickness.
Question 2:  Who really did this? It is someone framing Ryoga. I can't
think of anyone so wicked in the Ranmaverse, but whoever it is really
$#%@!ing hates Ryo-kun. See below.
 

2. The others are so angry at what happened to Akane that they drag Ryoga to
Jusenkyo

If they could get to Jusenkyo so easily, they'd go fix their own curses.
Anyway, who's "everybody?" Do the women do this also, or only the men?
Or, more likely for me, it's only one of the men. Your obvious choices: 
Ranma, Tatewaki, Soun, Happosai, Dr. Tofu.

and throw him into Pool of Drowned Girl, removng his pig-curse and
giving him the girl-curse, then rape him as an act of revenge. (Note:   Ryoga gets   pregnant.)

Again, it would be better to have just one of the men above turn
sadistic, rather than all of them. The ritual punishment you propose
darkly recalls Agatha Christie's _Murder on the Orient Express_, but
that story has already been done.

3. Ryoga is found to be innocent after all, but not until Akane finally wakes
up seven months later.

Why is she in a coma for so long? Does she know who actually did it?
What happens to the real rapist?

4. Ryoga dies in childbirth.

I think it would be more interesting if he survives and comes back for
revenge.
That's assuming there is only one person at Jusenkyo, although a _Hang
'Em High_ type plot might ensue if Ryoga was gang-raped there.

As for the real villain of the piece, who started the whole thing off by
assaulting Akane and framing Ryoga, I favor the Jusenkyo guide ("Ah, no
can eat this one, mother $#@#$!").

Suggestions are very welcome.

I suggest you don't write any version of this story.


DRM

-- 

My signature file, attending all mails:

If we shadows have offended,
Think but this (and all is mended,)
That you have but slumber'd here,
While these visions did appear.
And this weak and idle theme,
No more yielding but a dream,
Gentles, do not reprehend;
If you will pardon, we will mend.
And, as I am an honest Puck,
If we have unearned luck,
Now to 'scape the serpent's tongue,
We will make amends ere long:
Else the Puck a liar call.
So, good night unto you all.
Give me your hands, if we be friends,
And Robin shall restore amends.
                --Shakespeare, Midsummer Night's Dream