拿紙箱

How to get corrugated carton for bike in Japan
If you temporary need more soild box, get a corrugated carton for a bike.
Just visit a nearest bike shop, then tell then "JITENSHA YOUNO DANBOURU BAKO WO KUDASAI", which means "Give me a corrugated carton for bike".If they have, they give you it as free.
This bag is usualy too big for carrying. So it is reccomended to make it a bit smaller with knife and packaging tape("GAMU TEEPU" in Japanese).