How do I keep my cash safe in Japan?

If you're staying in a hostel around other foreigners, follow the typical advice to keep cash safe by not showing it off, keep it on your person, the usual. On the streets and on public transport, the chance of being mugged is vanishingly small and you can just keep it in your wallet if you like.

That said, Japan is only "cash-centric" in the sense that it's normal to pay for everything from meals to plane tickets with cash. It is not some backwater where credit cards have never been seen before. You will struggle in the smaller bars and cafés, and in the more rural areas. But at the same time, many places including hotels, the larger bars and restaurants, and the ubiquitous 7-11 stores also accept cards, and there are plenty of ATMs around, most of which will accept foreign cards. If you are staying near major urban centres, there should be no need to carry a huge quantity of cash with you, just enough to survive a few days.

Since Japan is a cash-based society, you will need to carry cash around. You can also put yen on your ICOCA card, since you will be mobile. I've put the website below.

https://www.google.co.jp/search?client=safari&rls=en&q=where+can+i+use+icoca+card&ie=UTF-8&oe=UTF-8&gfe_rd=cr&ei=IdHQWMaBN4SH2QTMn734Ag.

Your ICOCA card is a pass that you can use while traveling around the country, Though it is a 'safe' country, I have had my phone stolen here, it is safer than other countries but don't be lulled into a false sense of security. People are people wherever you go.

Safety shouldn't be a big concern in Japan, as there is little violent crime against individuals there. Just take your normal precautions: put your money in a wallet and keep your wallet in a safe place, preferably in your pocket (and take care of your pocket!); don't flash your money around; try to keep your bags in sight in crowded places. Having done these, you should be good.

I've once had over 20,000 yen cash right in my pocket in Tokyo and been perfectly safe, but of course I will not recommend this. Don't be like me!

Regarding the cash-centricity of Japan, many small dining establishments (e.g., street-side ramen restaurants & katsudon places) indeed accept only cash and Suica/PASMO. All major convenience stores (7-11, FamilyMart & Lawson), bigger restaurants and virtually all retail places do take credit cards (JCB and Visa, sometimes MasterCard and American Express), although many customers do prefer cash. Thus, if you wish, you don't need to have that much cash on you anyway. Around 10,000 yen of cash should be more than enough for you.

See if you can find a copy of the "Cool Japan" episode on money: http://www6.nhk.or.jp/cooljapan/en/past/detail.html?pid=161218

I remember watching it and it was quite common for Japanese people to carry around 40,000–70,000¥ ($400-700) in their purse or wallet.

That being said, a credit card is accepted in many, many places.... so don't worry. If you need cash, just go to the nearest post office (which is also a bank) and withdraw some cash.