The Stairs to Adulthood May Not Always Lead Up
Consists of episodes animated from unused manga chapters, before returning to the Silver Soul Arc on January 8, 2018. Porori is an Onomatopoeia for something (mainly water) falling.
Aired 02/10/2017EP 1 - The Stairs to Adulthood May Not Always Lead Up

2017
Gintama.: Slip Arc
Consists of episodes animated from unused manga chapters, before returning to the Silver Soul Arc on January 8, 2018. Porori is an Onomatopoeia for something (mainly water) falling.