It's the fore- and upperparts that normally attract attention when it comes to male Blue and Whites, so just to be different here's one where the underparts take centre stage. These blue centred longest undertail coverts came as a surprise, so much so that I was thinking "Do they always look like this and I've never paid any attention, or is this unusual?". Fortunately, it isn't something obvious that I've always overlooked and does appear to be unusual, although quite how unusual, I don't know. For what it's worth, I haven't been able to find any online images that match it. I saw this bird on 4th May in Kanazawa, Ishikawa.
What appear to be blue feathers, slightly masked by overlying white, on the lower breast also catch the eye.
Below is a female photographed the following day on Hegurajima.
