Buchou kara Gikei, Soshite Koibito!?

Overview

Her 32-year-old, high-spec boss is her ex-boyfriend and stepbrother!? Naru is a 28-year-old single employee working at a famous trading company. Her boss, Sasaki Tomoya, is 32 years old, a super elite department manager, and Naru's ex-boyfriend! The reason they broke up was because she was tired of playing the role of the perfect girlfriend. In fact, she loves beer and yakitori, and she doesn't want anyone to know that she's a lazy woman who barely cleans or cooks! One night, while enjoying her usual evening drink, Naru's mother suddenly tells her that she's getting remarried! It seems that her new husband will have a child... And his last name is Sasaki...? Surely... her stepbrother will be her ex-boyfriend and boss, Department Manager Sasaki?! Just living together is impossible, so to have the department manager become her stepbrother...?! That's just not possible! (Source: Daitosha/Shushuisha, translated)

Source: AniList