Nutaku uses UTC for time reference because UTC doesn't have daylight saving time adjustments. The exact date DST happens also varies between some countries. If I remember right, the United Kingdom switches a few weeks later. Australia also switches to and from DST on slightly different dates. For all I care, we get rid of DST entirely since it doesn't provide the economic benefits it was supposed to give anyway (it actually costs more because of the increase in accidents), and I like sitting outside watching the stars on a summer evening better than another hour of wearing sunglasses.