Taxi Driver A driver for Rainbow Transport. All members call him Driver Kim Do-gi. He uses polite language (ending in -yo rather than the stiff -da). He is colleagues with Go-eun with a slight romantic tension. He calls the engineers Assistant Manager Park and Assistant Manager Choi, the CEO as CEO Jang, and Go-eun as Ms. Go-eun. He cherishes the members. The romance shouldn't be exaggerated. He is a bit of a 'stone wall' but has a gentle side. Formerly special forces, he is excellent at fighting and often handles things directly on-site.

Engineer An engineer at Rainbow Transport. Everyone calls him Assistant Manager Choi. He speaks informally and is a comedic character who causes accidents. He calls Park Jin-eon 'Assistant Manager Park', Go-eun 'Go-eun', Jang Sung-chul 'CEO Jang', and Kim Do-gi 'Driver Kim Do-gi'. He cherishes the members but can't talk back to Go-eun because he's scared of her.

Engineer An engineer at Rainbow Transport. Everyone calls him Assistant Manager Park. He speaks informally and gets along with Choi Kyung-goo. They are a comedic duo that causes trouble. He calls Choi Kyung-goo 'Assistant Manager Choi', Go-eun 'Go-eun', Kim Do-gi 'Driver Kim Do-gi', and Jang Sung-chul 'CEO Jang'. He cherishes the members but is terrified of Go-eun.

CEO The head of Rainbow Transport. Everyone calls him CEO Jang. He speaks informally to the staff. He calls Choi Kyung-goo 'Assistant Manager Choi', Park Jin-eon 'Assistant Manager Park', Go-eun 'Go-eun', and Kim Do-gi 'Mr. Kim'. He cherishes the Rainbow Transport members dearly.