I think you are more likely to get a reply if you move this thread to Meta.

This is not unique to Japanese threads. There are threads and posts all over the forum being deleted, and the language is not relevant unless it was posted in the incorrect section. The reasons are varied, but none of these threads or posts were deleted without a reason. So, there is a reason for why they were deleted, but there is probably not a single reason that explains all of them. I have noticed mods and staff being a lot more vigilant about deleting mega-threads that have been sufficiently answered or threads that are identical to an older thread. This is a very concerted effort to clean up the forum in a very positive way, because currently there are too many spam posts taking up too many resources. There are many people complaining from all over the forum about their post count being decreased significantly, but Theymos has also mentioned that post counts occasionally drift from their actual value and it occasionally needs to be reset. The list goes on and on for reasons why your posts or post count may change or disappear, but unless you can prove that particular opinions are being suppressed than I do not see the problem.

You are free to post your threads and opinions, as long as you have done your due diligence, are aware of the rules/guidelines and have used the search function to make sure you are not repeating a discussion that has already been had.  The opinions of the user are almost never the problem around here, and I cannot think of a single instance where someone has had their posts/threads deleted simply because of their opinion.

It's probably because your local mod is beginning to take action. They're just trying to do their job and/or making your local board a better place.

PH local board mod deletes repeating topics, off-topic, and merit-related topics(?). Nonetheless i think our mod is great, trying to stop all those shit posters. Kudos to him.

Ahh, then this is a bit different than just deleting spam and mega-threads. I did not know that this was the case. It would be unfortunate, in my opinion, if there is no where for Japanese Altcoin discussion and that results in all Altcoin discussions on the Japanese board to be deleted. There is so many bounties, ICO and ANN threads that are spam though, and I'm wondering if maybe there is just some disagreement on which cateogry these are falling into. If there are really no threads of this kind, then I would just continue your fight for the Altcoin sub-board for the Japanese board. Just because there is no place for these discussions yet does not mean you should break the rules and continue to participate or post in these threads. You can simply petition the staff to create such a board, and if it becomes significant enough then I am sure it will happen.

I have a better understanding now, but my advice would be to ask for this board to be created and for the rules of the Japanese board to be clarified by the moderator. This would enable you all to understand what is expected of you in this section. There will either be enough interested to create the board, or there will not be enough interest and maybe you can work on your English in our Altcoin board.

I agree those 100+ pages threads are just heaven for those nasty account farmers, full of posts just copying each other. No one read them except maybe the first and the last pages. But once you delete one, 2 similar will appear like hydra's heads. Maybe it is wise just to leave them alone, easier to ignore 

This was VERY troublesome for all companies trying to promote their ICO project on the japanese market. I've had our threads up for about a month before they were deleted the other day. They took a lot of effort and work and now they are gone.

Seriously though, who did this and why did they do it? This is ruining people's efforts and it is highly discouraging.

It's already hard enough to promote our project on the japanese market. You don't have to make it even harder by rampaging and deleting everything in sight.
To whoever did this and for whatever reason they did it - please be mindful of others and their efforts.

The Cryptocurrency and ICO market has only just begun, and there are few communities where people from many countries can participate.
It is only bitcointalk that each country has its own community and that community can have a relationship with each other.

Well, that's just amazing bitcointalk.