If you look at the non-past negative case (~nai), the ~u verbs are all written with an 'a' before the nai. In the words you mentioned: kaerAnai, kirAnai,shaberAnai.
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If you look at the non-past
If you look at the non-past negative case (~nai), the ~u verbs are all written with an 'a' before the nai. In the words you mentioned: kaerAnai, kirAnai,shaberAnai.