:~$ ruby -v
ruby 2.6.3p62 (2019-04-16 revision 67580) [x86_64-linux]
:~$ irb
> require 'date'
=> true
> Date.today
=> #<Date: 2019-04-18 ((2458592j,0s,0n),+0s,2299161j)>
> Date.today.jisx0301
=> "H31.04.18"
> Date.new(2019,5,1).jisx0301
=> "R01.05.01"
new era for japan starting this may.
happy rubying.
--
many thanks and best regards,
--botp