Bundai is an overaggressive language teacher/tutor who kidnaps and force-teaches Mugen to read and write. His methods are seemingly extremely unorthodox, which includes punching the student in the face when they get a pronunciation wrong and intimidating them with an inferiority complex if they don't learn to read and write. Although, one might observe that this extreme method of "teaching" was Bundai's way of getting revenge on Mugen for sticking him with his bar bill. The night before Bundai had (drunkenly) harassed Mugen about not being able to read the menu, forcing him to drink a wine-like liquid while lecturing him on the "souls" of the letters.

His methods, however, seem to be very effective, as Mugen not only learned to read and write in a single day but (fictionally) created the infinity symbol, which he claims to represent his name.