In rooting around for videos on YouTube, I managed to find this one titled:
My first thought was 一二三? What name goes with that?
So, translating it (and hearing the announcers) and a search turns up that the person is Hifumi Shintarou pitching for Tokaidai Sagami (Kanagawa).
And interestingly enough, they're in the Kanto Super-Regionals! (They're facing Koufu Shougyou)
And one more thing? He seems to be one of the pitchers to watch in the region!