By Nagaru Tanigawa and Puyo. Released in Japan as "Suzumiya Haruhi-chan no Yuutsu" by Kadokawa Shoten, serialization ongoing in the magazine Shonen Ace. Released in North America by Yen Press.
The Haruhi franchise has always had one big problem, which is that the light novel and anime releases are generally (Endless Eight aside) fantastic, whereas the manga is merely a serviceable adaptation. The few places the manga has generally had time to shine is where the author is allowed to do his own occasional side-story original chapter.
That's why I was so pleased to see Yen license this. It's a 4-koma gag manga, based off of the original series, which runs in Shonen Ace alternately with the regular Haruhi manga. And being a gag manga, it's not restricted in any way, either by characterization (Yuki wouldn't do this!) or by plot. The result is pure fanservice in many ways, being essentially the artist reaching out and pushing as many fan buttons as he can, but given this is Haruhi Suzumiya, he has a lot to work with.
I won't lie, this isn't fantastic. The art is just as average as the regular Haruhi manga, but in a different way. And as with all 4-koma mangas, some gags simply don't work. But it's funny. Gleefully taking apart its source, this is a manga willing to have Haruhi accidentally roll down a flight of stairs, or have Ryoko come back as a miniature super-deformed version of herself. The essential thrust of the characterization is still there... Haruhi makes unreasonable demands, Kyon makes a sarcastic retort, Mikuru twitches and is tortured, and Koizumi smiles enigmatically.
Well, there is one glorious exception. Yuki Nagato is still her deadpan self, mostly. But then the artist does a gag comic which shows her playing an Ero Game instead of reading, and you can see the lightbulb go off over his head. Suddenly the idea of Yuki the otaku is born, and it leads to wonderful places. This is then combined with her interaction at her apartment with the tiny Asakura, where Yuki not only gets a well-deserved chance to be the boke in a tsukkomi routine, but actually has to control her laughter at some points. Mostly as seeing Asakura frustrated is just too adorable.
(Yuki, by the way, is also the star of a second spinoff manga, The Disappearance of Yuki Nagato, which runs in Kadokawa's seinen Young Ace. This one takes her 4th movie characterization and spins it into a light romantic comedy. I suspect Yen will license it as well once it has enough volumes.)
It's hard, as with many subjective 4-koma, to describe why I enjoyed this so much. And it's possible that the humor may not win over others. And yes, just as with its parent manga, the anime is even better, although there isn't the same major drop-off, just a minor one. But really, it's Haruhi with tons and tons of gags, super-deformed madness, and fun. Pandering of the best sort, the type that doesn't also offend the sensibilities. Heck, the light novel author in the afterward says he wishes his own series was more like this. Even if you've avoided the original manga, you should check this out.