While I was looking through Bun'ei Tsunoda's book 'Nihon no joseimei: rekishiteki tenbo' two months back, I found this very uncommon name in the section regarding female names from the early part of the Edo period (1603-1868).
It was written as しやうぶ or 志やうぶ (shiyaubu) since, back then, しょう (shō) was written as しやう, しよう, せう or せふ, but I would assume that, in kanji, it would have been written as 菖蒲 (Japanese iris).
One final note on this, this name is pronounced sho:-buu (or boo).
Anyway, WDYT?
My PNL:
http://www.behindthename.com/pnl/149249My blog:
https://maybeitisdaijirou.wordpress.com