4-banme no Kyokon Kouho

Despite being surrounded by wealthy relatives, Manami is extremely ordinary. She learns that, according to a long-standing agreement, someone in her family must marry the son of a wealthy company owner. However, she was relieved to be at the bottom of the list of candidates...but then she finds out that her potential fiancé is at the company where she started working, and of all things, she ends up becoming his subordinate! What's more, for some reason, he keeps paying attention to her at every turn, bringing them very close!?

(Source: Alpha Polis, translated)