Giko (aka. Giko Neko, Giko Hanyan) is a misanthropic cat who seems to run a bar. He is Mona's friend and Shii's boyfriend.
His catchphrase is "逝ってよし！"/"Itteyoshi". This is a pun: Normally it translates to "You may leave", but with this particular spelling it actually means "You may die".
Giko originated on Ayashii World, a precursor to 2ch. He was named after the phrase "ギコハハハ"/"gikohahaha" which was a memetic laugh at the time.
Interestingly, the creator of Giko mispelled "ギコ猫"/"Giko Neko" as "擬古猫". ギコ and 擬古 are pronounced the same, but 擬古 translates to "psuedo-classicism". Ayashii World users ran with this and made him say classic sayings with modern twists. However, this characterization was forgotten after he was picked up by 2channel, and he eventually became the suicide baiting asshole we all know and love.
