I like Japanese names myself, though I shy away from using them. In my opinion,
Aoi sounds pretty nice with your preferred names. I like
Kiku but it sounds juvenile and mismatched with
Isobel and your other names.
Yuki is cute, but very much overused. The meaning is quite pretty.
May I introduce you to
Haukea? It's also a pretty name- Hawaiian, though.
I do like the name
Ivy, though
Ivy Greene does sound strange. All in all, these are nice names but I'm uncertain as to how to combine them.