Hmmm... Interesting, and what a cast of suspects and possible motives:

(In no particular order. Note some motives are flimsy, but are possible
considering who it is.)

Ranma: Motive 1- Had it with the tug of war between the girls. He gives
them one moment of pleasure then offs them. Motive 2- Gets all warmed up
by either Shampoo or Kodachi and engages into some... activities. When
she threaten to tell Akane, fear and possibly rage causes him to kill
her. The sexual act brings out a need in Ranma that he repeats with
other girls.

Mousse: Shampoo's treatment of him and lack of care shown by other the
girls leads to him HATE all women.

Akane: Combine Ranma's other 'fiancees' constantly trying to steal the
man she loves with bi-sexual tendacies that she tries to hide and her
ease of getting irrationally angry. One moment of violence lead her to
kill one of Ranma's fiancees. Failing to be caught- she did it again.

Ukyou: With the signs of Ranma falling in love with Akane gets to the
point she no longer could deny it- she killed Akane and then started for
others that got in her way (Nabiki was probaly floater number 3).

Kodachi: Being of questionable sanity to begin with and that her love
has three women of superior claim, she might do something about the
competition.

Shampoo: Obstacles are for killing, and best to use means that leads
evidence of who did it to go elsewhere.

Cologne: Since Shampoo isn't doing her job of removing obstacles,
someone has to.

Kuno: Not completely sane and has... an odd outlook towards women. His
passions might have consumed him.

Konatsu: A kunoichi ninja who specializes in poison and arson with a
backstory that reads like Cinderella. With the unrequited love for
Ukyou, he offs her in jealous rage and killed more out of either desire
to be cuaght and/or to throw suspicions elsewhere. Not likely since his
characterization is of a traditional japanese girl, but you can't be
sure about the quiet, demure ninja- can you?

Tsubasa: Rejected by one to many women he returns to those that scorn
them and kills them.

Kasumi: Her facade for keeping the peace for her family breaks after her
sister's wedding was attacked. Kasumi the axe murderer arises as her
anger consumes her and removes those that threateb her family.

Nabiki: I don't think this would be her M.O. but that could be the
point. There is also the fact very little of Nabiki is actually seen in
the manga series, so her reasoning can be almost anything- including
that these girls are Nabiki's lovers who want to stop the relationaship/
something more from Nabiki/ to let others know about it.

Soun, Genma: Fed up with the interference to joining their clans, one of
the two (maybe both) does something about it.

Nodoka: Girls should know their rightful place in the culture. If they
don't, they need to be either corrected or have a second present to make
sure they can no longer make mistakes.

Happosai: The perverted lech is no longer satisfied with panties ups the
ante.

Ryoga: By suggestion of Sayuri and Yuka, P-Chan gets 'fixed' by Akane.
This causes him to want revenge and he kills them. While other motives
are possible, he wouldn't only be killing in Nerima... unless getting
lost is a lie to cover what he does.

Mikado: His need to kiss many women and now this are to make up for
his... failings as a man.

Azusa: She loves Mikado, but he'd rather kiss a complete stranger than
kiss her. Maybe if they weren't any other girls of the type Mikado likes
he'll kiss cute littl' Azusa.

Pantyhose Taro: He final told a girl that might like him his name... and
she laughed. She isn't laughing anymore.

Bakeneko / Ghostcat: His brides keep on rejecting him. If they don't
want to marry him, they must not want to live either.

Scary when you think about how easy it might be for some of them to go
off the deep end- ain't it?

-Lord Archive