Since that entry is from his Japanese Wiki page, I would need further verification to believe that he is 175cm
In any case, since you have lived and worked there, you know what I'm saying. The official line is that commitment and ritual are everything, that belonging and the group are paramount, and that hierarchy is respected. As another commenter posted, the reality is that it is only the image of these things that is the goal.
Once they've been in the system long enough, however, many of them become to believe, and to actually live, the image. This doesn't hold for the young, though. This guy hasn't even gone through university yet, that great Japanese holiday between exam hell and the start of the work life.
Again, I'm not saying that it is absolutely impossible for a 17.35-year-old to cleanly run a FAT 10.01 (+0.9). Similarly, it is not absolutely impossible for a 17.35-year-old Japanese to use PED's, or for there to be an error in timing or in his age calculation.
Japanese society tends to the monolithic, but there are exceptions. Teen sprinters tend not to run 10-flat, but there are exceptions. Kiryu is certainly an exception to many rules.