Along with Goku day (5/9) and Piccolo day (also 5/9) we now have Saiyan day 3/18 (318 = Sa-i-ya).
Just a note that most of the items below are Japan only so dont get your hopes up too high.
Campaign 1: Official Site x DBZ Dokkan Battle Collab
You can see here Toyotaro is definitely a Vegeta fan and hopefully he is able to give the Prince some more screen time and power ups. You can get this artwork as an in-gam wallpaper if you login to Dokkan battle between now and April 2nd.
Campaign 2: Reach 31800 likes and RTs in Dokkan battle. Not sure if this game is even available in the US, I assume it is, but if this goal is reached, players will receive in Game Presents.
Campaign 3: Is the Turn HUmanity into Saiyans project I wrote about earlier.
Campaign 4: Is the most interesting but three lucky fans in Japan will receive Goku’s special orange jacket.