If you read my previous post (Why you shouldn't come to Japan as a missionary), you might be wondering what's left to say on the question. But I've got two reasons why you most certainly should come (and they're not the great food and the hot springs...)
1. Your ministry among the Japanese is likely to be more culturally-nuanced and to bear longer-lasting fruit.
In my last post, I pointed out the statistic that a Japanese person is perhaps thirty times more likely to become a Christian outside Japan than inside Japan. That's probably true enough. But it's only half the story.
Of those Japanese who make a profession of faith in Jesus overseas and then return to Japan, perhaps four out of five will have no living connection with a church two years later. There are many reasons for this, including the fact that Japanese are often treated as "guests" in overseas churches whereas in Japan they face an "all-hands-on-deck" approach for which they are not prepared. Another reason is that well-meaning Christians overseas have little or no understanding of the cultural challenges and discipleship issues that will face returnees.
For example, one of the hardest areas of discipleship for new Japanese Christians involves how to relate their faith in Christ to traditional religious practices, especially those surrounding festivals and funerals. Most Japanese who return to Japan from overseas as new Christians have never thought through these questions.
In addition, it's not uncommon for Japanese to make "professions" of faith in a foreign language either with little real understanding of what they are accepting, or simply to be polite to the Christian who has been kind to them.
How can non-Japanese gospel workers help new (and old) Japanese believers? The many, complex, and multi-layered aspects of Japanese culture and language, especially as it relates to the gospel, can take years of hard and patient study even to begin to understand. With the best will in the world, it's next-to impossible to do this properly outside of Japan.
And apart from anything else, it goes without saying that it's only in Japan that you will meet the countless Japanese who either don't or won't or can't go overseas, including (but not of course restricted to) those who are often marginalised in society -- many children, the old, infirm, sick, the poor, shut-ins, and myriad minority groups and sub-cultures. All of them need Jesus.
2. There is a way to be (and to leave) a positive gospel influence in Japan for the long-term, and it might be by adopting the persona of the "wholesome foreigner."
This is an area I've got wrong in the past. In 2008 I moved back to Japan, already speaking the Japanese language pretty well, to study at a seminary in Tokyo. I was the only "white-man" in the place. (We did have one missionary sensei.) At that time I tried to act like "one of them." I tried to be, as far as I could, "Japanese." In my opinion, with the possible rare exception, this is not something missionaries (and non-Japanese Christians in Japan more generally) should aim for.
However much a non-Japanese tries, they will almost certainly never truly be accepted as Japanese. That was my experience, and it hurt a bit. But some time later an older, wiser missionary advised me that it was far better (for me, for the gospel, and for Japan) to try to cultivate the persona of the "wholesome foreigner." What does that mean?
Well, it doesn't mean not learning the language and culture, or not seeking to excel in these areas. The particular missionary who gave me this advice himself had a PhD in Classical Japanese poetry! It also doesn't mean "becoming something you are not." Rather, as I understand it, it's an application of Paul's principle of being "all things to all men" (1 Corinthians 9:22) for the Japanese context.
Inevitably, in Japan, most people will put foreigners in a "box" of some kind. The question is, what box do we aim to be put in? The way we live over the long term makes the difference, for us and for the gospel. On one level we might say, "Just be yourself." But can we be more specific about how that might work and what it might look like in Japan?
This veteran missionary observed to me that in Japanese history, the persona of the missionary as "wholesome foreigner" has left a deep and lasting impact on the country and its people. He (or she) has typically been respected as a humble, honest, committed, gentle, devoted, faithful, all-out disciple of Jesus Christ, one who has left a trail of blessing and encouragement in his or her wake. Such a foreigner is outlived by her legacy -- one of gospel blessing. The "wholesome foreigner" may never be a model for Japanese to copy precisely, but to the extent that he imitates Christ, he leaves an example of godliness that can be emulated in distinctly Japanese ways.
The "wholesome foreigner" isn't committed to a fixed pattern of ministry. One particularly effective way that missionaries in Japan can serve today is equipping and training Japanese Christians, in evangelism, in discipleship, in preaching, in theology, and in living the Christian life. This can often be done more effectively (and cost-effectively) in Japan than elsewhere.
The "wholesome foreigner" will always recognise that he is not "one of them" and so will not try to be what he is not. At the same time he won't assume the superiority of his own ways, or that he has all the answers. He'll commend his message and his Master by his exemplary life and witness.
I think there are almost certainly other "models" or "personae" that missionaries in Japan can adopt to help them situate their ministry here and to give them appropriate direction. You might like to share your ideas in the comments section below.
The reality is that long-term cross-cultural gospel service is hard work, whether you stay or go. God is calling some to stay so that they might reach Japanese for Christ, and some to go so that they might do the same. It's up to you - in dependence on the wisdom that God gives you and your church - to make the best decision in obedience to his call on your life.
May God use us all together, for his glory!