I hunted high and low in for XXL jerseys in Japanese stores and it seems that all cyclists in Japan are no larger than an M, with the occasional XL online.
I ended looking at stores online here and abroad and prices, as with all things cycling related, get high quickly.
I wanted a jersey that looked the part with a few sponsor logos / graphics, wasn't plain, possibly bright enough to improve safety. No, couldn't find exactly what appealed to me.
Hours of research later I decided that for the prices I was seeing I might as well make my own darn jersey. So I did.
A bit of a flaff time wise but turned out nice in the end. I converted the blue robot icon avatar I have here and on my teacher resources website into a jersey and mountain bike shorts.
I'm not cyclist shaped and didn't want a cling filmed looked so it's loose yet comfy in parts, but it's really nice in both warm, cold and humid weather with breathable fabric etc. Picture below. I'll try and get one of the back as there's 12" version of the logo on the back. The yellow circle against black looks nice and catches the attention of trucks drivers in tunnels I hope.