The main character from the [[Yotsubato!]]. A tiny five-year old girl with a distinctive [[green hair]] tied into [[quad tails]], resemble a four-leaf clover, fitting with her name. Also, apparently not a Japanese. 

[[4chan]] uses her as a mascot/on their 404 pages and hold her in high enough regard that asking for porn of her gets angry reactions and most often even bans.
よつば 小岩井よつば