Subordinating conjunctions in Japanese grammar are essential to connect clauses or sentences expressing relationships such as cause, reason, and purpose. They indicate that the following clause is a dependent clause and explain the relationship of the clause with the main clause. Some common subordinating conjunctions in Japanese are “ので” (node), “から” (kara), “が” (ga), “けれども” (keredomo), and “ために” (tame ni). These conjunctions play a vital role in providing context and meaning to sentences, making them indispensable in Japanese communication.