The feudal lord of the region, Ota Dokan, heard about this and began to worship at the shrine. Reportedly he donated land to the shrine and renamed it  Koamiyama Inari-in Manpukuji-ji. During the Keicho era (1596-1615) the surrounding locality was formally named Koami-cho and the shrine became the locality’s tutelary shrine. With the enactment of the  Distinction between Shinto and Buddhism Order in the early Meiji Period the shrine was named Koami Inari Jinja. It took  its current name of Koami Jinja when it registered as a Religious Corporation after the war.                                                                                           

In 1929 the shrine was rebuilt by the group of shrine carpenters led by Naito Komasaburo who had earlier built Meiji Jingu.  It was fortunate enough to emerge undamaged from WWII and is now the only extant pre-war wooden shrine building in Nihonbashi.  

Probably the main attraction of Koami Jinja is the small Benzaiten Well,  the Japanese name for which is "Tokyo Zeni-arai Benten," (東京銭洗い弁天) lit. Tokyo Money Washing Benten. The belief is that if you wash your coins in the well and replace them in your purse or pocket prosperity will ensue. 

The shrine's home page identifies Ichikishima-hime-no-mikoto with Benzaiten. This is not common, but does happen and the conflation seems to be based on the beauty and other aesthetic factors common to the two goddesses. When the shrine/temple components of Koamiyama Inari-in Manpukuji were separated in accordance with the  Distinction between Shinto and Buddhism Order, Benzaiten went with the temple. Very soon after this, however, the temple closed down and Benzaiten was enshrined again in what was then  Koami Inari Jinja.