From Viz:
On the surface, Satoko has it all she’s beautiful, the daughter of a nobleman, and at a prime age for marriage. Unfortunately, she is also quite ill and only has a short time left to live. Before she can secure a marriage that will redeem her worth in her family’s eyes, she finds herself the target of the mysterious assassin Shinpei, and her plans are put in jeopardy. In order to save herself, she makes a desperate proposal of marriage! When it comes to love, however, Shinpei takes “until death do we part” seriously.

Original Web Manga
Official English

Note: Nominated for the 48th Annual Kodansha Manga Awards in the Shoujo Category in 2024.