Kuse Tsuyoi Shuzoku de Gyouretsu ga Dekiru Kekkon Soudansho

After the end of the war between the races, the seventeen races established the experimental city of Myth, where all races can live together as equals. Years later, people of all races come to the famous marriage agency in this city, which claims to have a "100% client satisfaction rate." Anya, an cat-girl apprentice staff member, works day and night to help the mysterious and beautiful director, Donna, and the scruffy guidance counselor, Shaw, to bring couples together, no matter what race they may be.

(Source: Dengeki Bunko, translated)

Note: Winner of the Silver Award in the 29th Dengeki Shousetsu Taishou.