Chikuhi-sen (Fukuoka-Karatsu) 筑肥線　（福岡　－　唐津）

The Chikuhi-sen offers a direct railway link from Kyûshû's capital city of Fukuoka (with over one and a half million inhabitants) along the northwestern coast through the port town of Karatsu into the northern parts of present-day Saga Prefecture and to the town of Imari. However, since the complete restructuring in 1983 of the section from Fukuoka to Karatsu it is better to consider this part of the Chikuhi-sen as a separate line. It is the only line in Kyûshû electrified with direct current (DC 1500 V). Trains are thus able to continue their journey into Fukuoka using the Fukuoka Municipal Underground Railway.

Today the Chikuhi-sen (eastern section, opened 1923-1926) consists of the line to the east between the town of Karatsu and Meinohama in Fukuoka (42, 6 km). On the western side trains continue over the Karatsu-sen to Nishi Karatsu (West Karatsu, 2, 2 km), where also a rolling stock maintenance depot is located. On the eastern side, trains go on from Meinohama over the Underground Railway to Hakata (i.e. the eastern side of the city of Fukuoka and the region's main railway station) and Fukuoka Airport / Fukuoka Kûkô (13, 1 km). (The Underground line from Hakata to the airport opened in 1993). Originally, trains started at Hakata station and used a track bed through town to Meinohama; this line closed in the restructuring of 1983. Large-scale realignment also took place on the Karatsu side; Karatsu used to be reached via a switchback station on the right side of the estuary. Important sections of the line around Meinohama, as well as the entire new entrance to Karatsu and Nishi Karatsu are now elevated lines permitting fast running.

The line from Fukuoka as far as Chikuzen Maebaru is suburban in character and frequently served by both JR and Fukuoka Underground trains. In 2005 a special station was added to give access to the new campus of Kyûshû University (Kyûdai Gakken Toshi).

Through trains from Fukuoka Airport to Nishi Karatsu are worked by JR sets every half hour. There are also local stopping JR trains on the section from Chikuzen Maebaru to Nishi Karatsu, which is very much more rural in character and runs much of the way along the sea coast.

The name of the line, Chikuhi-sen, refers to the two old provinces of Chikuzen (written 筑前), the western part of modern Fukuoka Prefecture, and Hizen (written 肥前), present-day Saga and Nagasaki Prefectures, a central town being the traditional port of Imari. Together, the characters 筑 and 肥 are read "Chikuhi".

＃ The line was interrupted between Shikaga and Hamasaki east of Karatsu through landslides triggered by torrential rain (6 July, 2018). Train set 303-3 was badly damaged. ＃