ALL "X's" unless otherwise noted are Kotaro Oshio's 
famous(ly difficult) "nail attack." This is a technique 
that is done by "slapping" with your right hand the 
strings with the nails of your middle and ring finger so 
as to produce a percussive noise or a muted noise, as 
the case may be. 

It is hard to do at first and feels very unnatural 
, so I recommend practising and watching his videos. 
Your two fingers should be curled, and then should 
slam the strings on the nail. 

This is an advanced song. Good luck!