Habits can be a dangerous thing.
It was a reasonably nice day in Rome, and despite having studied and lived in Europe for several years, Shiro's half-awake body automatically assumed walking along the left side of the hallway, like he would in Japan.
Which is problematic if you cut a corner and someone else is walking on the right.
His pleasant musings about what to have for lunch were rudely interrupted by a sudden collision with a white pillar. No, not a pillar. It was softer (be it only slightly), and pillars don't go "oompf" when you bump into them.
Nor do they give you a death glare while rubbing their stomach and re-adjusting their atti