Probably a safe guess that "shi-" means death, or at least a pun on death.
According to the artist's comment on CraftifyX, it's meant to be read as a homonym of 死の旗 (another phrase for "death flag") while otherwise being a normal Japanese surname.
篠秦幸江 (Shinohata Sachie) - 篠: bamboo grass - 秦: manchu dynasty, name given to naturalized foreigners, also used as the Japanese equivalent to the Chinese letter Qin - 幸: happiness, blessing, fortune - 江: creek, inlet, bay, large river
篠秦幸江 (Shinohata Sachie) - 篠: bamboo grass - 秦: manchu dynasty, name given to naturalized foreigners, also used as the Japanese equivalent to the Chinese letter Qin - 幸: happiness, blessing, fortune - 江: creek, inlet, bay, large river
Taken from Jisho.org
Qing (with a 'g') is the Manchu dynasty, and the last imperial dynasty. Qin (without a 'g') is the first imperial dynasty, the one started by Qin Shihuang.
This critical mistake appearing in various online English sources is probably inherited from James Heisig's Remember the Kanji.
As for the "naturalized foreigners" bit, it probably refers to the Hata clan, a prominent ancient Japanese clan that immigrated from Korea. (They claim descent from Qin Shihuang himself, but this whole bit doesn't add up since the Emperor himself has a completely different surname.)
