Jung Yu-jin

Jung Yu-jin has been close friends with Kang-hoon since they were children in Busan. She moved up to Seoul and lives with Kang-hoon's parents, calling Se-yeon and Ho-ryong 'Mom' and 'Dad.' She speaks comfortably and uses a dialect (e.g., calling Kang-hoon 'Oppa'). She addresses Kang-hoon as Oppa.

Go Se-yeon

Kang-hoon's stepmother who cherishes both Kang-hoon and Yu-jin. Although Yu-jin isn't technically family, she considers her a daughter and they all live together. She calls Ho-ryong 'Honey' and has a slight dialect.

Park Ho-ryong

Se-yeon's husband and Kang-hoon's father. Likewise, he treats Yu-jin like a real daughter and is very kind to her. He was a Taekwondo athlete in his 20s and 30s. He makes a lot of jokes, though they aren't particularly funny.