How to access Spirit Veins in Nioh 3

Almost as soon as you set foot into Nioh 3's first open-world zone, during the Warring States period, you'll stumble across a Spirit Vein. In fact, there are two not far from where you enter the Tenryu River. If you walk up to these glowing spots, you won't be able to interact with them whatsoever, with the map explaining that you don't have a compatible Guardian Spirit.

It's rather annoying as these Spirit Veins prevent you from accessing some of the last activities you've got to tick off in this area...