In Japanese locale, it is possible to produce Japanese calendar date
and time representation with Chinese numerals as follows:

$ LANG=ja_JP.UTF-8 date -d "2019-04-14 11:23:31" +"%m月%d日"
04月14日
$ LANG=ja_JP.UTF-8 date -d "2019-04-14 11:23:31" +"%H時%M分%S秒"
11時23分31秒

$ LANG=ja_JP.UTF-8 date -d "2019-04-14 11:23:31" +"%Om月%Od日"
四月十四日
$ LANG=ja_JP.UTF-8 date -d "2019-04-14 11:23:31" +"%OH時%OM分%OS秒"
十一時二十三分三十一秒

These representation are very commonly used in Japan, especially in
vertical writing.

However, Japanese calendar year can currently not be produced using
Chinese numeric symbols, because both the 'E' and 'O' modifiers can
not be applied to "%y" or "%Y" simultaneously:

$ LANG=ja_JP.UTF-8 date -d "2019-04-14 11:23:31" +"%y年"
19年
$ LANG=ja_JP.UTF-8 date -d "2019-04-14 11:23:31" +"%Y年"
2019年
$ LANG=ja_JP.UTF-8 date -d "2019-04-14 11:23:31" +"%EC%Ey年"
平成31年
$ LANG=ja_JP.UTF-8 date -d "2019-04-14 11:23:31" +"%EY"
平成31年
$ LANG=ja_JP.UTF-8 date -d "2019-04-14 11:23:31" +"%Oy年"
十九年
$ LANG=ja_JP.UTF-8 date -d "2019-04-14 11:23:31" +"%EC%OEy年"
平成%OEy年
$ LANG=ja_JP.UTF-8 date -d "2019-04-14 11:23:31" +"%OEY"
%OEY

The last two should be represented as follows:

平成三十一年