Gensokyo is doing round 2 of soul training for new humanity. This time it's red cat souls. They said it's because they are following the Sunflower standard of being representative of all beings to maintain legitimacy. The most popular humanoids are black beastcats and red beast ladies. Although the latter normally have short tails and are something in between cats, foxes and other steppe living creatures, the kind of soul chosen for summoning is here referred to as red cat for simplicity.
They will do the same as the black cats, possessing NPCs to learn and to form a hivemind and a collective subconscious. They will mainly act as assistant souls, only sometimes assuming the main soul role of a person. Their nature is "heavier" so they are closer to infernal dimensions than the black cats. This makes them good, solid assistants.
All humans will be offered one, and if they are able to become immortalized during training, they will stay with that person. Some will also likely stay as walk-ins with already solid walk-in black cats and some will be alone.
This is the next step. After this, the plan is to summon a "rainbow cat" which is the same as a white cat. But to make it clear that white has all colours, we will break the spectrum into a rainbow.