Amazon Japan has started taking international pre-orders for the upcoming May 2019 issue of CoroCoro Comic in Japan.
The May 2019 issue of CoroCoro Comic comes with a download code to redeem the Mecha Gear in Splatoon 2. The Mecha Gear is the winning design of the CoroCoro Comic Splatoon 2 gear design competition.
Keep in mind the code is region locked to Japanese versions of Splatoon 2.
Pre-order the book here (ships worldwide).