The character you are refering to is "Miruru." 
She seems to have 'various' roles with respect to
Noelle and her family ^_^;;  She appears early on
in the series, so there should be a lot of cels of
her, so I would advise just waiting for the right
update.  However, she is "big-breasted" and a cat
girl, so perhaps she's popular .

Keys
She's not quite my type...