Aoi-gata (葵形) literally means "hollyhock shape". This style of tsuba was since ancient times mounted on tachi (太刀), large swords that were worn edge downwards, slung from a belt, mainly by cavalry. It is also known as tachi-mokkō-gata (太刀木瓜形) or "Tachi cross shape".1
Three tachi style tsuba in aoi-gata.
A tachi sword. Metropolitan Museum, New York. Accession number 07.109.5.
Blade 13th century, by Naganori. Mountings 18th to early 19th century.
Gift of the family of Dr. Francis E. Doughty, 1907
1. Markus Sesko; Koshirae, Japanese Sword Mountings, Lulu, Inc. 2014. Page 78.