From Shogakukan Asia:
Hitoyoshi Yokoya is a high school student who currently lives alone. One day, an unfamiliar girl knocks on his door and offers to be his maid. She reveals that she is a former assassin, which makes Hitoyoshi nervous. But when her skills save him from being run over by a truck, Hitoyoshi ultimately decides to take her in. However, the mysterious girl actually has no household skills. In fact, her only expertise is assassination, as she has lived her entire life for the sake of killing. Nonetheless, her time with Hitoyoshi allows her to experience new emotions she had never felt before, inspiring her to become a regular girl. Told from youth that her only worth is as a killer, Yuki had known nothing else except cold efficiency and following orders. Now that she has a chance to leave her past behind, she arrives at the doorstep of Hitoyoshi Yokoya, asking to be employed as a maid? Thus begins the journey of a former assassin learning what it means to be ‘normal’!

https://www.cmoa.jp/title/211101/