I recently opened a Rakuten Credit Card account and am being sucked into the complex Rakuten multiverse

Has anyone had experience of Rakuten point investing like this and can offer advice? Am I better avoiding Rakuten Securities completely and doing something else with the points?
I have zero investments aside from my ordinary pension in Japan and the UK so I am a newbie to investing too, just want to get started if I can.
For info:
https://www.rakuten-sec.co.jp/web/style ... tment.html