Umineko no Naku Koro ni (うみねこのなく頃に?, lit. When the Seagulls Cry) is a Japanese murder mystery doujin soft visual novel series produced by 07th Expansion. The first game in the series, Legend of the Golden Witch, was first released at Comiket 72 on August 17, 2007 playable on the PC; the game sold out in thirty minutes. The story focuses on a group of eighteen people on a secluded island for a period of two days, and the mysterious murders that befall most of the people. The goal of the game is to discern whether the murderer is human or of some other supernatural source. Umineko is the third title in the When They Cry series, preceded by Higurashi no Naku Koro ni and Higurashi no Naku Koro ni Kai, and followed by Umineko no Naku Koro ni Chiru.

A manga series adapted from the games began with three different artists working separately on different story arcs and is published by Square Enix. Additional manga have been published by Ichijinsha, Kadokawa Shoten, and ASCII Media Works. A 26-episode anime series produced by Studio Deen and directed by Chiaki Kon aired in Japan between July and December 2009.

This is the only info I found on Wikipedia.

While I, myself watched only like 15 episodes, I can already tell the anime is great. I didn't play the Visual Novel, but I do plan to. The opening for both, is also very epic.
I recomment this anime to anyone that likes blood, mystery and good story. It also has some epic moments... like this one screenshot I saw...

The subbed image version of that had something around the lines of...
"His Magic Resistance Level! It's over Endless Nine! ( :9000: )"
Overlay, the only thing I have against it, is the annoyance of Maria, and the censure (although sometimes it is needed.), along with fact that pretty much everything has the same breast size.

Hope you decide to watch it, and like it. Episodes can be found on Youtube.



Soucres:
Wikipedia and ytimg.com