Japan Airlines Domestic

Japan Airlines Domestic Co., Ltd.
日本航空国内線
*Nihon Kōkū Kokunaisen*
Commenced operations	May 15, 1971; (amalgamation; as TDA - Toa Domestic Airlines); April 1, 1988; (as Japan Air System (JAS)); April 6, 2004; (as Japan Airlines Domestic);
Ceased operations	April 1, 1988; (as TDA - Toa Domestic Airlines); April 6, 2004; (as Japan Air System (JAS)); October 1, 2006; (merged into Japan Airlines);
Hubs	Osaka–Itami; Tokyo–Haneda;
Secondary hubs	Fukuoka; Kagoshima; Sapporo–Chitose;
Focus cities	Osaka–Kansai; Tokyo–Narita;
Frequent-flyer program	JAL Mileage Bank
Subsidiaries	Harlequin Air (1997–2005); Hokkaido Air System (1997–2006); Japan Air Commuter (1983–2006);
Fleet size	81
Destinations	46
Parent company	JAL Group
Headquarters	Ōta, Tokyo, Japan
Website	www.jas.co.jp

Japan Air System (JAS), later known as Japan Airlines Domestic from 2004, was the smallest of the big three Japanese airlines. In contrast to the other two, JAL and ANA, JAS' international route network was very small, but its domestic network incorporated many smaller airports that were not served by the two larger airlines. As an independent company, it was last headquartered in the JAS M1 Building at Haneda Airport in Ōta, Tokyo. It has since merged with Japan Airlines.

JAS was famous for its variety of aircraft liveries; Amy Chavez of The Japan Times described the rainbow liveries as "abstract." Many of its color schemes in the 1990s were designed by film director Akira Kurosawa.

The airline's slogan was "Good Speed Always".