I thought morning sun and afternoon shade would be good too, but apparently the tree disagrees. Koto no Ito is a very thin-leaved linearilobum type, so I believe it is less sun-tolerant than many varieties.
I am pretty sure it is a sun issue, as the leaves are developing orange and red tones, particularly the top ones exposed to more sun. This wasn't something the tree did before once it was past the new-growth stage. Additionally, (and the cause for concern - I don't really mind orange tones
) the strongest colored leaves are turning crispy and brown in a way that to me looks like sunburn.
I don't see any wilting, which is what I would expect if it was not taking up enough water, right?
Here is a terrible image:
(note the curled up leaves in the bottom right - those are some of the ones with actual damage)
