Yes, this is native speakers of Japanese applying a sound law pervasive in their native language (that the consonant /s/ cannot occur before the vowel /i/ and must turn into a sh sound), and applying it to English, which does not have that sound law and that happily allows /s/ to occur before our /i/-like vowels.

An equivalent phenomenon going the other way (at least for American English speakers) is clearly distinguishing また mata "again" and まだ mada "yet" - American English speakers tend to merge /t/ and /d/ in that kind of intervocalic position (think about pronouncing "latter" and "ladder" identically), and it takes deliberate effort to pronounce distinct /t/ and /d/ sounds there in Japanese, where the American English sound law that merges them does not apply.