Sorry for being away from this for a while. First the easy parts...
1-3, and also 6, would seem to be normal, or that they would aid/facilitate or go along with normality (in school life).
Also, you mention "a bully" in your first post, and here, in 7-8, it is being generalized as "children prone to violence" and "violence culture". Hopefully, it is just a problem with one student, that as you mention, could be dealt with separately--something specific to this one student.
• And the important question/point(s): Keeping 3 in mind, 4-5 make me wonder--how is his english writing? And secondarily, his reading in either language? And what is "curcly numbers"--is that curly/circle-y, or what?
So his speaking ability seems fine, but he has trouble with apparently 'strict' writing tasks/requirements (japanese). Which is why I ask about his english writing--how is he doing with that? This is the internet, and the posts here are the scarcest of evidence, and this is not at all my specialty, but if he has any trouble with english writing (and reading in either/both languages), then my wonderings jump to the possibility of dyslexia (which has many forms). And on the side of those thoughts, your mention that he 'does curcly numbers', which also may indicate some kind of difference in visual processing.
I guess that's it. Apart from writing, can he read in japanese--kana? Can he read in english? Does he write in english? Can he recognize individual numbers, and say what they are in English or Japanese?
Again, this is the internet, musings based on the smallest bits and pieces, so this could be way off the mark.