With his last breath, Soma himself strictly ordered Matsu 'not to breath a word of it,' and since Matsu kept his order until she died, the details and motive as well as the temple where he was buried are unknown to date.
その際、相馬自身がマツに「他言無用」と厳命し、マツが生涯その命を守り通したため、自殺の詳細や動機、また菩提寺については現在に至るまで不明である。