Legally, Dad (2020)

Other name: Step Dad On Paper , Seoryusang Appa, 서류상 아빠

Synopsis:

Orphan Ah Young is a financially struggling 23-year-old who takes care of her 8-year-old sister Dan Bi while juggling part-time jobs. One day a 28-year-old man Yoo Sang appears in front of Ah Young offering to be her dad through a signed agreement.