I have just finish reading Onani Master Kurosawa very recently, and now Im kinda addicted to manga with the final pairing hard to predict or even unpredictable.
Need help on other manga with that kind of ending. No spoiler please. 🙂

Cat Street is the closest one I can recall...

Honeymoon Salad.

[img]http://media.tumblr.com/e43f35cfdd762cc666571a6dd0f163d5/tumblr_inline_mhbel8Cy8V1qz4rgp.gif[/img]

Not sure I would recommend Honeymoon Salad since

there isn't really a final pairing in that.

I'm interested in more manga like this as well. Ichigo 100% is the only one I can think of off the top of my head.

Sir, you just spoiled the series for the thread starter.

[img]http://media.tumblr.com/e43f35cfdd762cc666571a6dd0f163d5/tumblr_inline_mhbel8Cy8V1qz4rgp.gif[/img]

Edited, but the point of my post was that it doesn't totally fit the criteria of the OP, and I feel like it would be unsatisfying for him in that regard.

Well, its okay. At least the spoiler tag is used.
So if I still read it, its my curiosity that kills.
BTW, ichigo 100% isnt really unpredictable. Because most of the reader would predict from between the two main heroine. ALthough my prediction is wrong. But I kinda hoping that there are also other series that giving surprise, if for Ichigo 100%, the final pairing is to be with the 3rd candidate (Satsuki Kitaoji). Now thats what Im looking for.
BTW, have you read Onani Master Kurosawa? The final pairing is sooo good (for me at least).

Quote from Great

BTW, have you read Onani Master Kurosawa? The final pairing is sooo good (for me at least).

I think it's good more for the 180 turnaround and the character development that entails than merely because it was unpredictable.

Hmmm, I dont really understand it myself, what makes me think its good.
Is it the character development? The from dark situation to light condition? The unpredictable final pairing? Or maybe it is because the girl looks so damn cute and lovable (although I dont like the

bullying & smoking girl type)
But if I think about some other manga with their final pairing, I think I would like it more if its not them that they choose. For example :

Ichigo 100% : the final pairing is with Tsukasa Nishino, many other fans are guessing/predicting/hoping it suppose to be with Toujo Aya (including me), but the truth is, I actually want Satsuki Kitaoji to be the final pairing.
Love Hina : Instead of Narusegawa, how about Shinobu.
Ai Kora : Instead of Sakurako, why not Yukari.
Midori no Hi Bi : the Title already showing Midori is the winner, but I still want a surprise of Takako Ayase being the final pairing.
Mx0 : I know, the ending is vague, still obviously, the final pairing is with Hiiragi, but I want it to be with Naomi Mizuki, or better, with Lucy!
Pretty Face : Again, the ending is vague, but Im pretty sure the final pairing would be with Rina Kurumi, but are there any chances for the other candidate to even win/step in the throne? Maybe Natsuo? Or better, with Kurumi Yuna! Thats for another surprise.

I hope I manage to deliver the message. 😛

I LOVE THIS MANGA!

I listen to 2NE1 (a korean pop girl band) while reading this manga, it was amazing, how their songs perfectly match the manga, its message, and the feelings the manga wants to convey to the reader.

I totally recommend to listen k-pop, and also listen it while reading manga.

Honestly, I don't think Onani Master Kurosawa's pair to be unexpected, but well...
I can say that I can't really think of anything in the shounen/seinen section like what you asked. Also in anime the only pairs that really surprised me are from Kannazuki no Miko when it aired in 2004 (WARNING! If you plan to watch it, don't read any summary nor look any info, not even the manga page here on mangaupdates otherwise you're gonna spoil it. You've been warned) and Shuffle.
I'm not gonna say anything about them to avoid the slightest spoiler, I know they both have manga but I didn't read them and I can't say if they have the same ending that the anime.

In shoujo/josei maybe there are more, but I read few of them, so I'm hardly an expert. I can say that Usagi Drop could be considered unexpected if you want to try it.

Just for reference, the most unexpected pair I've ever witnessed is in the JRPG game Lufia 2.

What I like in Trivial Pursuit style. Pick your category:[img]http://i379.photobucket.com/albums/oo233/Reid4891/Manga/trivia-1.jpg[/img]

Moe Kare!!-very girly and shoujo-like, but it's the closest thing I can think of that fits your request.

[img]http://img267.imageshack.us/img267/4466/princesswallpaper2560x1.jpg[/img]

"In a world where most people would be crazy, then it would be normal to be crazy and crazy to be normal... but then again, if you were normal, then you would be crazy... isn't it crazy what a paradox a little craziness can create?"

Oh yeah, I already read Usagi Drop quite along time ago, and the unexpected final pair is also impress me. (in other word, I like it, unrelated whether its wrong or right)
Im gonna try Cat Street, Honeymoon Salad and Moe-Kare, but my reading waiting list are already too long, I dont know when can I finish it all. But I can skip the list anytime. Just like when Badkarma suggesting about Onani Master Kurosawa, I skip my list and read it after I finish read Ichigo 100% and Im happy I have done it.
btw, I dont understand what bibisuki mean. Which manga is Loved? OMK?

School Days and Yubisaki Milk Tea would fit in that there's no clear pairing until near the end, but I'm hesitant to recommend those two since they're not for everyone. I can, however, recommend Otaku no Musume-san. The amount of plot twists in that is pretty lulzy.

Thank you. Im adding School Days, Yubisaki Milk Tea and Otaku no Musume-san to my never ending expanding "manga list to read next". 😀
Oh, and dont worry, Im not part of the "for everyone". Im kinda one of the "anykind of manga are readable"
So my policy is; Read First, Reaction later. 😛