[Grue3]

Oh, I just remembered another fun feature of Japanese verb conjugation.

Can you conjugate the (regular) verb "へる" (heru)? There happen to be two verbs that are pronounced "heru" but with completely different conjugations! Do you remember which one is which? In fact any verb that ends with -eru or -aru can be potentially conjugated like an ichidan verb or a godan verb. For each such verb you have to remember its conjugation class, lest you conjugate it completely wrong. So these aren't so regular after all.

Also a related topic is intransitive/transitive verb pairs. These are also heavily irregular, and you must use the correct one in a sentence or it will be ungrammatical.