The minimal amount of white makes it more a Hi Showa. (People will debate the amount of white that can be visible and still be considered a Hi Showa.) Unfortunately, it is difficult to tell the quality of the red pigment in most photos, which is key to long term enjoyment. The Sumi is still "young", but reasonably well distributed in an old-style pattern I find attractive. I generally do not care for Hi Showa. My personal preference is for at least 25% white above the lateral line. Many people like Hi Utsuri, but the tendency of that variety to have poor, orangish Hi and speckly Sumi eventually causes most folks to lose interest in them. The Hi Showa tends to avoid these problems (but not always). So, for a person who likes the look of Hi Utsuri, but not the price of the few quality specimens occasionally available, the Hi Showa provides a nice substitute that can be enjoyed far longer. Hi Utsuri also tend to suffer from thin peduncle somewhat similar to Shiro Utsuri. The Hi Showa tends to avoid that hurdle as well.
Enjoy your Showa and please post a progress photo when it reaches 20". While it is not to my personal taste, I expect I'll really like the Sumi pattern after two more growing seasons.