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Personification of the Swiss Arms 550 rifle from the manga and anime upotte!!, almost always addressed as "shiggu." She wears the standard red bow, white shirt and green skirt as the other junior high kids at her school, and has black hair that she keeps in a covered bun. She is a standout member of just about every extra-curricular her school offers, most notably the marksmanship team. She is portrayed as cool, calm, capable and confident.
She's also intensely arrogant. She's snide and aloof with with everyone- even her "friends", she arrives late to every sports match her team competes in, she harasses her teammates, cheats in competitions, is disrespectful to her opponents, is a sore loser and caustic winner, and bypasses all rules and standards because she views herself as above them.
The author/artist of Upotte (Tennouji Kitsune, better known as "eggplant") is a big fan of the actual SG 550, and his interest bleeds through to the character shiggu. Unfortunately despite being an airsoft and deactivated enthusiast he has no experience and little knowledge on firearms, and his ignorance, like his interest, bleeds through to his work and expecially the character of SG, who gains exaggerated skills from Eggplant's perception of the real SG. Most notable is SG's sniping talents; the real SIG550 utilizes a special cartridge which gives it increased long-range abilities; Eggplant, uninformed about the specifics of the cartridge, gave SIG a MOA of around .2 and an effective range of around two miles- both drastically inflated from the truth.
SG's sour personality, exaggerated skills and the author's exaggerations have earned her the adoration of some but the hatred of most, and she's collected many nicknames, such as "deus ex shiggu", "marry shiggu" "ugly and unworthy" "Shoddy and Gawdy #550" and others.
An extremely common misconception among Upotte fans and gun enthusiast is that the SG 550, and therefore shiggu, Is made by Sig Sauer. This is untrue. Sig Sauer only makes the 556, an import legal copy- the "SIG" part of SIG SG 550 stands for "Schweizerische Industrie Gesellschaft", the original makers.