There are different styles: The 間道 (=東京) style 長命寺, using thin pancakes to wrap the あん, and the 関西 (=京都) style using 道明寺 flour.
間道
This was supposedly invented in 1717 by a monk at 長命寺 in today's 東京, who picked up fallen cherry leaves, preserved them and used them for this sweet. People cruising the river lined with cherry trees would get off their boats and eat this sweet. This predates the 関西-style 桜もち.
➡️ I find this more elegant than the chew-y, rice-y 道明寺 variation; but I also had them sitting by the river watching the sun set, so that certainly helped.
関西
For 5 pieces:
Make syrup with 17.5 gr sugar and 90 gr water. Add some food colouring (in my case, half a drop of Migros food colouring). Heat to dissolve.
Add this to 50 gr 道明粉. Cover in plastic wrap and let steam for 5'.
Make a 1:1 syrup to work it. Use about 25 gr of dough to 15 gr of 中あん.
While traditionally, こし餡 is used, I like the idea of using 桜 petals (5 gr to 100 gr 白あん). Like this, you have the whole 桜 in your sweet.
Argyi has a more complicated recipe that heats on the stove, rests for 2 hours and then steams the dough for 10'. It tastes rice-ier and is more annoying to work with, so I think the method above is just fine.
However, the idea of using 桜 petal あん I got from him.
Leaves