Whats's the order of K-project manga? I want to read the K Project manga, but there are a lot of series. So what's the order for these series?
If you mean publication order, the K wikipedia article's manga section doesn't list all the publication dates, but seems to list them in publication order.

By serialization publication start date (end date included if applicable/known):


2012 ? (no later than November) - 2013 ? (tankobon release 2013 April): K Stray Dog Story
2012 May - 2013 July: K -Memory of Red-
2013 October - 2014 July: K -Days of Blue-
2013 December - 2015 April: K - The First
2014 January: Gakuen K
2014 June: K: Lost small world
2014 December - 2015 July: K: Countdown
2015 April - August: K: Missing Kings
2015 May - November: K: Dog and Cat
2015 September: K: Dream of Green
2015 October: K: Return of Kings


Sources: K Project wikipedia article and Anime News Network Encyclopedia.

Based on the various summaries and news articles, I've placed them in approximate chronological order (some of the stories overlap) using the anime series as a guideline.

Before K TV


K: Lost small world
K -Memory of Red-
K -Days of Blue-
K: Stray Dog Story


Adaptation of K TV


K - The First


After K TV / Before Movie


K: Dog and Cat


Adaptation of K Movie


K: Missing Kings


After Movie / Before K TV2


K: Countdown


Before and/or Overlaps with K TV2?


K: Dream of Green


Adaptation of K TV2


K: Return of Kings


Alternate story


Gakuen K (comedy spin-off where all characters attend high school together)