We're sorry, but currently you can't use this emoticon in Markua:

¯\_(ツ)_/¯

The only solution right now is to do an inline image of the emoticon:
​
​http://help.leanpub.com/en/articles/3919168-how-do-i-insert-an-inline-image-in-markua

And yes, we get the irony that our answer here is basically ¯\_(ツ)_/¯.
​