Kishikoku Saikyou Reijou ni Yoru Ken to Ken to Renaijutsu

The young lady Olivia is constantly surrounded by unsavory rumors and is feared by those around her. In order to improve her relationship with her fiancé, Prince Luke, she proposes a duel with him on the condition that the winner will get one wish from the loser. When Luke accepted, he thought she was planning to break off the engagement and he was determined to do so whether he wins or loses, but what does Olivia really want?

(Source: Comic Zero-Sum, translated)

Note: Serialized version of the one-shot originally published in the "Akuyaku Reijou desu ga, Shiawase ni Natte Misemasu wa!" (悪役令嬢ですが、幸せになってみせますわ！　アンソロジーコミック) anthology volume 4.