O-Train(중부내륙순환열차, Middle Division Inter Land Cycling Train), is a tour train that uses the circle shaped railroad. It was made by Korail, in April 12, 2013. It is almost a fraternal twin to Nuriro. Citizens also think this train is shaped like a squirrel, so they say it is also called "Squirrel Train". It is a trunk-line electric car, and the seats are similar to Saemaul's suite seats. O stands for "O"ne, also meaning to circle around.
The train starts from the Seoul Station, making a quick stop at Chunglyanglee Station. After the Chunglyanglee Station you go to the Jehcheon Station, and this is where they start in the circular route. If we start from the right, it is Jehcheon-Danyang-Poongee-Yeongju-Bonghwa-Choonyang-Booncheon-Yangwon-Seungbu-Cheolam-Taebeck-Choochun-Gohan-Mindoongsan-Youngwul-Jehcheon. It goes around four times. The V-Train uses this route, from Yeongju, passing Bonghwa and Choonyang, stopping at Booncheon-Yangwon-Seungbu-Cheolam, and then going back. It's because these stations contain valleys.
- The appearance difference between O-Train and Nuriro is O-Train is green instead of blue, and the yellow and orange parts are close to the engineer's door. On the front it says "Let's Korail" instead of the Korail logo(some of them only contain Korail logo). In the O-Train's passenger car the walls and the floor of inside is made out of old-fashioned wood, while Nuriro's passenger car inside is made out of metal or plastic.