rotating horizontal axis text in multilevel

hi
I have created a chart and the horizontal axis looks like

|          |    item2_1   |  item2_2  |         |
|   item1  |            item2       an|other_ite|m

I want to rotate the text of "item1" and "another_item" however when I select horizontal axis options, only item2_1 and item2_2 can be rotated.

I have attached a picture of my chart. Is there any way to arrange the texts?

Only inner labels will rotate.

If you want full control you will need to fake the axis with data labels or textboxes.