We do not know what a KIKIYAMA is. It is speculated that it is either Madotsuki or a person who just happens to be a game designer unusually good at weird scenario writing.
KIKIYAMA is also the creator of Yume Nikki.
For a very long time, it was thought to the English community that KIKIYAMA had no form of contact, as their website hasn't been updated, and the only mention of them in public was a possibly apocryphal interview said to be from a Japanese website. However, a recent thread on Uboachan revealed that all this time, their email address was available. A member contacted KIKIYAMA and asked them whether or not they would update the game, and it was confirmed that Yume Nikki would make it past version 0.10, albeit very slowly.
Recently, a link was posted on Uboachan to a MySound profile and Pokebis thinks it's KIKIYAMA. Link here.
It seems like the account doesnt exist anymore, as the host site went down a few years back. It can be accessed in part using the Wayback Machine (http://waybackmachine.org/).
Fortunately, KIKIYAMA was not involved in the 2011 off-the-Pacific-coast-of-Tohoku earthquake , as they were far away from the affected areas.
Official Website
KIKIYAMAHP is KIKIYAMA's official website pertaining to Yume Nikki. It can be found here: