Well as luck would have it, it doesn't look like he'll mature to be large enough to compete in the ring. The NIPPO standard calls for males to be 52cm, and allows +/-3cm, however he will probably reach just around or below the 49cm lower end of the standard. This is of course an unknown, as he could have some miraculous growth spurt. However, from decades of experience, the concensus is that he will not be large enough.
He's a beautiful pup with a friendly and energetic temperament. If there is anyone out there looking for a nice companion Shikoku male for the cost of export (and perhaps a nominal rehoming fee for the breeder) I'm trying to find a home for this guy as soon as possible.