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Looking into potential relatives: that site lists two people, Nobue Brown and John Washburn.
Nobue Brown works as Associate Dean for Business Affairs at McCombs School of Business in Buda, Texas. Looking at the faculty website, she is listed as Susie Brown. Here's the real kicker: her full name on intelius is "Nobue Sato Brown". Age is listed as 65.
John Frederick Washburn apparently owns some Mineral Rights in Buda Texas: https://www.mineralholders.com/texas/buda/john-frederick-washburn/1407693. genealogy.com lists John Frederick Washburn as being married to a Norma Kay Grigsby with whom he has three children (none of whom are Masamune). Since he is 69, he could be the grandfather or genealogy could be looking at a different John Frederick Washburn.
I wouldn't jump the gun to say it's necessarily Carlton Washburn, because who would use his mother/grandmothers's middle (or maiden) name in a nickname? It could also be e.g. his father. But it seems fairly certain that Masamune is somebody from that family.