Playing shiritori can't be this cute
Talking about shiritori, Japanese syllable starts with a vocal alphabet or a consonant that followed by a vocal alphabets, so when Mie said "Komura-kun" she ends it with a "n" syllable which is a single alphabet without any vocal alphabet after it. Komura can't continue with the word that start with "na", "ni", "nu", "ne", or "no" because "n" is different syllable with all of them