Convention of Tianjin
After the Gapsin Coup, Li Hongzhang of Qing and Itō Hirobumi of Japan agreed to withdraw both armies from Korea and to notify each other before sending troops again.

大日本國, 大清國 · Public domain · Source
Japan had already extracted an indemnity and funds for a new legation from Korea in the Treaty of Hanseong (1884). The Tianjin convention gave Japan the same right as Qing to send troops to Korea.
When Qing troops landed at Asan at the Korean government’s request during the Donghak uprising of 1894, Japan invoked the convention to land troops at Incheon, leading to the First Sino-Japanese War.