Based on the report provided by the survivors of the mikan vessel, the Shogunate dispatched an exploration ship to survey the uninhabited islands. The ship’s captain was Shimaya Ichizaemon, who set sail from Shimoda on April 5, sailing via Hachijojima, discovered the present Chichijima on April 29, where he laid anchor in Futami harbor. (Ref 1, 2)

He first landed on the island on May 1, and explored the main islands such as Chichijima and Hahajima for approximately one month. Shimaya and his crew surveyed the size of the islands, and also clarified the location of the uninhabited islands by measuring their latitude, as well as measuring their distance from Shimoda, Hachijojima, Miyakejima, and other islands. On Chichijima he released three roosters and two hens. Moreover, on Chichijima he erected a shrine and invoked the three deities of Hachiman Daibosatsu, Amaterasu Omikami, and Kasuga Myojin, writing on the side of the shrine “Dai Nippon no Uchi nari” (Part of the Great Japan). He also brought mountain betel palms, mulberry logs, and birds from the island to present to the Shogunate. (Ref. 1, 2)
 
Furthermore, Shimaya named each island Chichijima, Hahajima, Anijima, Ototojima, Anejima, and Imotojima respectively, and decided the name of places such as Omura, Okumura and Susaki. (Ref. 3)
 

Ref. 1:“Shimaya Ichizaemon’s notes on his sailing to an uninhabited island,” Historical records of the Ogasawara Islands, vol. 26

Ref. 2:“The story of Shimaya Ichizaemon’s sailing to Islands” Nagasaki sosho (Nagasaki Collectanea Series), Part 4, vol. 6 (1894), pp. 11-16

Ref. 3:“Mapping and deciding the name of places by exploring the entire Islands of Ogasawara,” Historical records of the Ogasawara Islands, vol. 2