Hi postalpicker and all,
This is a Japanese datestamp - Bisected Circle type datestamp, vertical version (listed as"JBC-2" in Handbook of Japanese Postmarks, 2008). The structure of the datestamp is depicted in the following image .
This JBC-2 is further subcategorized into 3 (three) subtypes, and yours is the small format, "Month" type used from Meiji 27 (1894) to Meiji 36 (1903).

The date is June 27, Meiji 31 (1898). Post office is "Ecchu Fukuno postal & telegraph office", which is now Toyama prefecture, Fukuno city. This is a very nice example of a full stroke, sock-on-the-nose datestamp so please admire its beauty !!!
Further information:
The postmark JBC-2 was introduced in 1885 and was, as mentioned by other expert members, originally used for receipt of money order charges, where the postmark was applied directly onto the receipt document itself.
Since 1890, payment of money order charges by postage stamps were permitted, and since then we can find this postmark on postage stamps for obliteration.
Since 1894, this postmark was also used for postal savings. Furthermore, since March 1990 the payment of postal savings by affixing postage stamps to dedicated postal saving sheets were introduced, and this postmark was extensively used to obliterate the stamps on postal saving sheets.

Hope this helps you !
Greetings from Osaka, Japan
- unechan