Abstract
This paper investigates how essay writing by intermediate non-kanji Japanese learners is influenced by handwriting, smartphones, and PCs. We analyzed text length, orthographic and conjugation errors, and predictive conversions in essays written by 10 learners, using their process data. Kanji was used 2.2 times more, with higher accuracy, on smartphones and PCs than with handwriting. Notably, about 20% of smartphone predictive conversions occurred without any input. Conversion functions support writing; however, teachers should consider learners’ autonomous expression choices when selecting media in classroom settings.