Proper form of なさる - なさります or なさいます?

Question

In Genki II (second ed.), page 168 we are given polite forms of some verbs, among them する with なさる. They have also written that some of them have irregular conjugations in long forms, among them なさる, which becomes なさいます. However, in tangorin.com the conjugation table says なさります while Jisho.org recognizes both as forms of なさる. At the same when I type なさります or なさいます into google.com I get about 900 000 or 600 000 results respectively. Are both forms correct? Or is one of them just a common mistake?

Answer 1

When you start doing honorifics, there are extra verbs that conjugate in unique ways. なさる becomes なさい or なさいます. The ancient version of なさります feels more like Shakespearean English.

There are some other, more familiar, verbs that conjugate in the same way.

くださる becomes ください or くださいます

ござる becomes ございます

いらっしゃる becomes いらっしゃい or いらっしゃいます

Answer 2

なさります and なさいます are both correct, the former is still used, but the latter is the modern Japanese which became the standard over the time (and that is why in the textbook like Genki)probably it is simply easier to say or hear vowel い than り.

I hope this helps.