A clause in Japanese is completed when the final verb in the sentence is in the ใฆ-form. This indicates that something will follow the clause, as by itself this completed clause is not a completed sentence.1
Example: Yui is reading a book and...
็ต่กฃใกใใใฏๆฌใใใใงใใฆ
Info
็ต่กฃใกใใ (Yui + friendly honorific) is marked with ใฏ and thus is the topic of the sentence.
Due to the lack of an explicit subject, it is inferred from context in this case to be ็ต่กฃใกใใ.
ๆฌ (book) is marked by ใ, marking it as the object of the sentence.
ใใใง (reading) is the ใฆ-form of ใใ (read). The ใฆ-form here is placing the verb into the continuous present. As it cannot be the primary verb, it is adding context to the proceeding verb ใใ (exist).
ใใฆ is the ใฆ-form of ใใ (exist). As it is modifying what would be primary verb of the sentence, the ใฆ-form in this case is completing the clause and implying something else follows.