Utatane is a Windows OpenNap client developed in Japan, and available in English translation. Circa the year 2010, 3 000 Utatane users could be found on the Japanese servers, sharing upwards of 10 million files or 2 petabytes of files. Utatane was developed by #Rufu, and meant to be an improvement on WinMX, which can also connect to OpenNap. 1.043 was the last version to be released in 2006.
Utatane can connect to multiple servers, allows for automatic uploads to buddies ("Auto Users" who are added to a Hot List), clickable URLs in channels and private message windows, easy resumption of transfers, and has the ability to copy and paste text like windows, etc., and the saving of search results as a file for future reference. A user guide is included in the installation file. The user can choose to allow uploads to start automatically, or can allow only those who have been promoted to Auto User status. Unlike many P2P clients, Utatane allows users to search through the search results.
Connection information for English and European servers are found in .wsx files on WinMX or on the WinMX World Archive. There appear to be four public Japanese servers that are still online in 2019: ENDLESS, Kiss Only One Lady(KOOL), Kujira (lit. whale) and Ont2ch.