I cycled to Ueno today and by chance in the park was an amazing bonsai display. They are all satsuki (I am not sure how they differ from tsutsuji) but both, I think, are translated as azalea. Satsuki is also the old Japanese for May (now blandly called the 5th month). I can see why the month is named after them. Despite my scepticism here, I concede, they really are beautifu.