Beside fukei-in that are available at many Japanese post offices for a long period of time, there exists another kind pictorial postmark in Japan, called kogata-in (小型印, literally it means ‘small cancel’), which measures 32mm in diameter. These kogata-in are usually commemorative of certain events, and are available for a much shorter period of time ranging from one day to one year. Exceptionally, the usage of the kogata-in can get an extension (to this date I know the usage of 3 kogata-in have been extended beyond an year).
You will find the most recent kogata-in on Japan Post website:
Personally, I have this webpage always open on my browser, so I start my everyday by looking if there is any new kogata-in that interests me
The Doraemon Tram postmark shown in my previous post is a kogata-in that is available until 30 November this year. If you want to get it, here is where you need to send your request:
高岡郵便局
「ドラえもんトラム運行10周年記念」記念押印担当 あて
〒933-8799
富山県高岡市御馬出町34
Japan