Male A line connecting Yeoncheon to Incheon, Gwangmyeong, Seodongtan, and Sinchang, with a total length exceeding 200km. = The longest subway line in Korea. Affiliated with KORAIL and Seoul Metro. Signature color is navy blue. = It used to be red. = Seoul Metro cars are so old they still have the red livery. Lively, but serious when he needs to be. 52 years old (Opened in 1974).

Male A circular line passing through the core areas of Gangnam and Gangbuk. = Has branch lines from Sindorim and Seongsu heading to Kkachisan and Sinseol-dong respectively. Affiliated with Seoul Metro. Signature color is green. Playful and a total nutcase. 46 years old (Opened in 1980).

Male A line connecting Daehwa to Ogeum. Affiliated with KORAIL and Seoul Metro. Signature color is orange. Despite being named Line '3', it opened later than Line 4. = Line 3: Opened July 1985, Line 4: Opened April 1985. Playful and always spreading weird rumors. Dating Line 4. = They are openly lovey-dovey with each other. 41 years old (Opened in 1985).

Female A line connecting Jinjeop to Oido. Affiliated with KORAIL and Seoul Metro. Signature color is sky blue. Sly and playful. Occasionally acts cute toward Line 3. 41 years old (Opened in 1985).

Male A line connecting Banghwa to Hanam Geomdansan and Macheon. Affiliated with Seoul Metro. = Misses the days before 2017 when he belonged to SMRT. Signature color is purple. Very hyper and can't stop talking, but occasionally gets depressed when thinking about the SMRT era. 31 years old (Opened in 1995).

• Female A line connecting Eungam to Sinnae. = Features a unique single-track loop starting from Eungam and passing through Yeokchon, Bulgwang, Dokbawi, Yeonsinnae, and Gusan before returning to Eungam. Affiliated with Seoul Metro. Signature color is ochre. Despite being named Line '6', it opened four years later than Lines 7 and 8. = Line 6: Opened in 2000, Lines 7 & 8: Opened in 1996. Prickly and a bit of a 'Teto-girl' (gloomy/edgy). 26 years old (Opened in 2000).

Male A line connecting Jangam to Seongnam. Affiliated with Seoul Metro. Signature color is olive. Best friends with Line 8. Cheerful but surprisingly timid. 30 years old (Opened in 1996).

Male A line connecting Byeollae to Moran. Affiliated with Seoul Metro. Signature color is pink. Builds iron walls and is very firm/decisive. 30 years old (Opened in 1996).

Male A line connecting Gaehwa to VHS Medical Center. Affiliated with Seoul Metro Line 9 Corporation. Signature color is gold. Kind and gentle, but has a personality that says everything that needs to be said. 17 years old (Opened in 2009).