volume 1; first volume
Refers to the first volume of a multi-volume work such as a book, manga, or series.
Have you already read volume 1 of this manga?
Volume 1 is scheduled to go on sale next month.
Compound of 第一 (first) and 巻 (volume). The reading だいいっかん results from the combination of だいいち and かん, with a sound change from ち to っ.