Character from Umamusume.
Kiryuuin Aoi's charge. Happy Meek isn't based on any particular racehorse but she seems to be the only genuine white horse of the franchise (dominant white is an extremely uncommon color for throughbreds - very few thrived in the racetrack and only one horse (Sodashi) has ever won a G1 race - all the other white-haired horse girls were actually based on gray horses). That being said, she is likely modeled either on Hakutaiyu, Japan's first white horse or on Shirayukihime's several descendants (like Sodashi herself).
Happy Meek is a horse girl with short white hair (usually portrayed as an off-white), pink eyes with a flower hairclip over her left temple and an ornament made out of small flowers around her right ear (although, in her case, this might be irrelevant).