音節 おんせつ主音 しゅおん てき子音 しいんでしょう
onsetsushuon tekishii ndeshō

Noun
Desu Copula

Expresses probability in a polite manner ("probably…") of 音節主音的子音

1. Probably the syllable's main vowel's initial consonant.

Polite
Presumptive
Conjecture