noun
preface; foreword; introductory chapter
Refers to the opening chapter of a book or a formal introductory section. Often used in literary or academic contexts.
この本の序章を読めば、全体の構成がわかる。
If you read the preface of this book, you'll understand the overall structure.
論文の序章で研究の目的を述べた。
I stated the purpose of the research in the introductory chapter of the thesis.
noun
Figurative use for the initial stage of something, such as a project, era, or story. Less common than the literal book sense.
これはまだ物語の序章にすぎない。
This is still just the beginning of the story.
Compound of 序 (jo, 'order' or 'beginning') and 章 (shō, 'chapter'). The kanji combination directly yields the meaning 'introductory chapter'.