Also known as: ころんば
A retired UTAU composer who used to upload songs on Niconico. Has suddenly deleted all of their videos circa 2014, but their songs maintain cult popularity to this day, to the point that covers/MADs/YTPMVs (most notably Iwashi ga Tsuchi Kara Haetekurunda) and tribute songs are being frequently made (some even having relatively difficult-to-search titles). They are also the creator of the Yume Nikki fangame LcdDem.
Within the UTAU community, their name is generally considered a forbidden word, and is commonly known by the alias "K-san" or "xx".