This study focused on two forms expressing the “beginning” of the situation, -shihajimeta and -shihajimetatokoroda, and considered their differences. In previous research, -shihajimeru is considered to express the so-called“ starting phase” of the situation, although the actual use of -shihajimeta and -shihajimetatokoroda shows that -shihajimetatokoroda expresses the “starting phase” of the situation. I argue that -shihajimeta expresses“ transition to this situation” as an event. In addition, the sentence type differs between -shihajimeta and -shihajimetatokoroda. Thus, the difference in sentence type could be related to the type of adverbs that co-occur in each form and the different functions the forms play in discourse.