Metronome is a story written by Hana Chikai and illustrated by tashigi. It ran in Issue 11 at http://s2b2.livejournal.com/54743.html, and is mirrored at http://www.shousetsubangbang.com/mirror/metronome/.
From pinboard.in: "Strangers crashing into you and then asking for jackets probably isn't a coincidence."
From pinboard.in: "Ming Wei having crashed himself into Ben and impressed by Ben's designed jacket commissions him to make a jacket for a cosplay costume."
Metronome is followed by Warmth.