In the anime and manga, Robin is introduced as Chocolat and Vanilla's guardian in the Human world (- and later on as Saule and Houx's caregiver as well). His name can also be romanised as "Rock 'n' Lovin'", from Japanese.
It is apparent, that he is one of the most powerful wizards in Le Royaume - since he was able to fight Glacé by himself, towards the end of the series.
In the Human world, he is a famous rock star - and he is supposedly the wizard from the magical world; whom collects more hearts than any other witch or wizard, with his job.
He is seen throughout the series - especially, in the anime, to have a throng of female fans surrounding him. He can collect hearts very easily, in enormous quantities.
His heart holder is found inside his ring and he is rumoured to be about 6,000 years old. Facial marks are supposedly what helps retain his youthful appearance.