So I just noticed that the Digimon Adventure tri streams are region locked (thanks to a post on another Digimon website warning people against discussing how to bypass the region lock)
So instead I'm going to recommend people use hola if they wish to watch it. A chrome add-on.
Download Chrome if you don't have it, get hola unblocker (something I use for stuff like watching crunchyroll/US netflix

), make sure you're logged into nico and then select hola -> Japan and it will make the website think you're from Japan.
Pretty sure this isn't against the rules here since we talk about it for netflix/CR/Steam a lot.
If you do that anyway, you can then watch the streams when they start in May