Horse oil(Mayu), which is obtained as a byproduct of horses, is called a skin panacea due to its excellent efficacy and has long been exclusive to royalty and aristocrats.
In order for this precious Horse oil to be passed down to the common people while avoiding the eyes of the upper class, it hid the word Horse oil and got a new name: Toad oil.
'Tookup', which contains the meaning of 'Toad', the beginning of Mayu's popularization, has the symbolism of being the original of Horse oil.