Is in sao post-sao arc when kirito just instinctively does a little sword move and puts it on his back, just to remember he doesnt have a sword holder anymore ( idk what its called) but its just so cool and cute and awesome ill try to find a video if i can its just my favorite detail Edit- i found a video of it- i recommend the whole vid for viewing experience but im specifically talking about the moment at time stamp 1:20 its just so labels;inefectividad https://youtu.be/nj7og8nzz4g