Hakutaku

Hakutaku is a Celestial Beast and pharmacist living in Togenkyo at the Sentou Farm in Heaven. He took in Momotaro as his assistant and has been imparting his skills to the ex-ogre slayer ever since. He dwells among rabbits who also learn medical skills from him and aid him in preparation of herbal concoctions. Hoozuki is his arch-nemesis despite their many similarities.
(Source: Hoozuki no Reitetsu Wikia)