Well, I think it is big in China as well. The computer power for Bitcoin mining is certainly based in China and not in Japan. However, from what I can tell there is an economy (i.e. you can buy items at stores, have ATMs that Bitcoins). In addition, another reason that increases the use of Bitcoin in Japan may be that lot of affluent Chinese Bitcoin investors use their bitcoin when they visit Japan. The Chinese government enforces capital controls over the YUAN. You can only invest a limited amount of YUAN outside of China a year. When you invest in Bitcoin your limited amount of YUAN turn a profit and you can spend them without government inteference. It could be one of the reasons why a lot of Bitcoins are used in Japan. In Germany, for example, I have never seen a Bitcoin ATM, however I do they believe that they exist in Germany. They just may be less common.
About auto-investing. All though I do not invest into specific currencies automatically I always buy a certain amount of bitcoin every month to invest into other crypto currencies (like EOS, XRP and XLM). However, at the moment, I think it is a better strategy to buy Bitcoin and Ethereum only. I think this is the case, because Bitcoin will become more valuable after the SegWit#2 solution is implemented and when the blocks get bigger. Therefore, I would advise to buy and hold BTC/ETH at the moment and buy other cryptos once the growth spurt in Bitcoin ends. You can re-invest some of the gains made by Bitcoin into currencies that grew less than Bitcoin in that time.
I would also recommend to buy yourself into steemit. I think its an incredible crypto currency that offers a lot of advantages.
I do not know the other crypto currencies you just mentioned, but chances are that they are not going to make changes that are as drastic as Bitcoin. They probably behave more tamely so that you can invest in them later. Obviously there is guarantee for that and this is only my opinion. I do not know these currencies well enough to give you any advice on them.
Ripple (XRP) and Ehtereum (ETH) are competing against eachother. Ripple is not as far developed as ETH but I see the potential for a Black Swan event. However, since the price for XRP is very low compared to ETH it does not cost you much to invest into Ripple. Nevertheless, it is a smart idea to hold your ETH, for now, it will grow and is much safer than XRP. I use a small amout of money from my job each month to increase my online holdings. I do not sell any ETH to buy XRP.
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