I'm pretty sure everyone on Pinterest who sews children's clothes has pinned this tunic. I have the beautiful Japanese book the pattern came from. I even traced out the pattern last year, but I wasn't loving how the yoke had so many pieces.
After making Simplicity 2689 last year I realized there was a much better way to make a similar tunic.
I used some soft denim for the tunic and before I sewed the side seams I sewed some vintage ribbon I found on Etsy to the yoke. So I didn't have to cut the ribbon (in case I ever want to remove and reuse it) I mitred the corners.